F 271 
S22 
opy 1 



Issued June 30, 1913. 



U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ANIMAL INDUSTRY.— Bulletin 165. 

A. D. MELVIN, Chief of Bureau. 



THE MANUFACTURE OF CHEESE OF 

THE CHEDDAR TYPE FROM 

PASTEURIZED MILK. 



BY 



J. L. SAMMIS, PH. D., 

Associate Professor of Dan y Husbandry, College of Agriculture', 
University of Wisconsin, 

AND 

A. T. BRUHN, 

Expert Cheese Maker, Dairy Division, 
Bureau of Animal Industry. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1913- 



Issued .Imi" 31, I"!'' 



U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ANIMAL INDUSTRY, —Rui.iF.TiN ]<3=>. 
A. D. iMELVIN, CHihF oi- Bureau. 



THE MANUFACTURE OF CHEESE OF 

THE CHEDDAR TYPE FROM 

PASTEURIZED MILK. 



BY 



J. L. SAMMIS, I^H. D., 

AssocJafe Professor of Dairy Husband r\\ Collej^c of Aj^riaiiiure, 
( 'niversity of II 'isconsiit, 

AND 

A. T. BRUHN. 

Expert Cheese Maker, Dairy Dix'ision, 
Bureau of Animal Industry. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1913. 



THE BUREAU OF ANIMAL INDUSTRY. 



Chef: A. D. Melvin. 

Assistant Chief: A. M. Farrington. 

Chiff Clerk: Charles C. Carroll. 

Animal Husbandry Division: George M. Rommel, chief. 

Biochemic Division: M. Dorset, chief. 

Dairy Division: B. H. Rawl, chief. 

Field Inspection Division: R. A. Ramsay, chief. 

^feat Inspection Division: R. P. Steddom, chief. 

Pathological Division: John R. Mohler, chief. 

Quarantine Division: Richard W. Hickman, chief. 

Zoological Division: B. H. Ransom, chief. 

Experiment StatioJi: E. C. Schroeder, superintendent. 

Editor: James M. Pickens. 

DAIRY DIVISION. 

B. H. Rawl, chief. 

Helmer Rabild, in charge of Dairy Farming Invesligatiovs. 

S. C. Thompson, in charge of Dairy Manufacturing Invcstig-Jions. 

L. A. Rogers, in charge of Research Laboratories. 

Ernest Kelly, in charge of Market Milk Investigatin}}^. 

Robert McAdam, in charge of Renovated Butter Inspection. 

9 



D. OF 0. 
JUL 1i 1313 



LETTER OF 'I RANSMITTAL. 



U. S. Department of Agriculture, 

Bureau of Animal Industry, 

^Vasliington, D. C, January 30, 1913. 

wSir: T liavo tho honor to transmit for publication as a bulletin of 
this bun^au the accompan^ano; manuscript entitled "The Manufac- 
ture of Cheese of the Cheddar Type from Pasteurized Milk, " by Prof. 
J. L. Sammis, of the College of Agriculture, University of Wisconsin, 
and Mr. A. T. Bruhn, expert cheese maker in the Dairy Division of 
tliis bureau. The work herein described was con(kictcd at Madison, 
Wis., in cooperation between the Dairy Division and the Wisconsin 
Agricultural Experiment Station. 

The Dairy Division has been represented at Madison by L. D. 
Bushnell, Alfred Larson, and Miss Alice C. Evans, bacteriologists, in 
succession; S. K. wSuzuki and E. F. Flint, chemists, and J. W. Moore, 
F. W. Laabs, and A. T. Bruhn, expert cheese makers, in succession, 
all of whom have assisted at various times in this work. The Wis- 
consin Station lias been represented by Prof. Sammis, who from the 
beginning has had charge of the cooperative experinients in tlie manu- 
facture of the Chechiar type of cheese from pasteurized milk. 

The comj)arison of this cheese with tliat made from raw milk by tbe 
regular factory method has been systeniatically and thoroughly 
carried out under a variety of conditions by the use of (hiplicate vats 
of milk, one of these being pasteurized in eacli instance. During 
1910 and 1911, especially in the latter year, the \\v\\ |)rocess was per- 
fected and a large quantity of the pasteurized cheese was ma(h^ under 
commercial conditions and placed upon the open market. The 
results are fully described, also the proc(>ss of making the cheese, 
and it is shown that the use of pasteurized milk is highly satisfactory 
and economical. As pathogenic bacteria have been found to survive 
for several months in cheese made from raw milk, the pasteurization 
of milk in making cheese is also desirable for the protection of the 
healtli of the consumer. 

Respectfully, A. D. Melvin, 

Chief of Bureau. 

Hon. James Wilson, 

Secretary of Agriculture, 



CONTENTS. 



Page. 

Introductory 9 

The need for a new method of cheese making 9 

Faults to 1)0 corrected in milk for cheese making 10 

The necessity for the pasteurization of milk for cheese making 11 

Amount of heat necessary to destroy various bacteria 12 

Previous attempts to make cheese from pasteurized milk 13 

Dithculties met in making chcsese from pasteurized milk 14 

Difhculties overcome by acidulation of pasteurized milk 15 

The pasteurization process 18 

Pasteurization in a discontinuous or "held" pasteurizer 18 

Continuous and ' ' held ' ' pasteurization compared 18 

Selection of best temperature for pasteurization in the continuous machine . 20 

Objections to higher temperatures than 160°-165° F. for pasteurization. ... 23 

Effect of pasteurization on the properties of cheese curd 25 

The different types of continuous pasteurizers used 28 

The acidulation jjrocess 28 

The standard acidity of milk for cheese making 28 

Comparison of different kinds of acid for cheese making 30 

The ))roportion of hydrochloric acid required daily 30 

Testing milk for acidity 31 

Preserving the tenth-normal solution 32 

Diluting normal alkali to tenth-normal 32 

Adding acid to milk after pasteurization 33 

Calculating the amount of acid to be added '. 33 

Preparation of normal hydrochloric acid in the cheese factory 35 

General directions for pasteurizing and acidulating milk 37 

Making ready to pasteurize 38 

Starting and stopping the pasteurizer 39 

Starting and stopping the acidulator 40 

The use of bacterial starter in the new process 40 

The reason for adding starter in making pasteurized-milk cheese 40 

A practical sterilizer for the cheese factory 42 

Preparation of the starter 43 

Method of making cheese by the new process 45 

General arrangement of schedule 45 

Uniform proportion of color used in 1911, and rennet required 46 

Adding starter, color, and rennet to the milk 47 

Cutting, stirring, and heating the curd 48 

Drawing the whey, matting, cutting, and turning the curd 49 

Milling, salting, and hooping the curd 49 

Pressing and dressing the cheese 50 

Drying, paraffining, and curing 50 

Branding and selling the cheese 51 

Testing cheese for moisture when dressed in the hoop 52 

5 



6 CONTENTS. 

Page. 

Results of two years' trial of the new method 53 

Increased yield of cheese obtained by the new process 53 

Apparatus and methods of study 53 

Search for systematic errors in experiments on yield of cheese 56 

Shrinkage before paraffining, and yield of paraffined cheese 60 

Shrinkage and yield of cured cheese 62 

The causes of the increased yield from pasteurized milk 69 

The losses of fat from vat and press 69 

The increased moisture content of pasteurized-milk cheese 73 

The quality of pasteurized-milk cheese 75 

Scores and criticisms of pasteurized and raw milk cheese 75 

Cheese cured at Madison at normal temperature 75 

Cheese cured in the South 79 

Cheese cured in warm room at Madison 84 

Cheese cured in cold storage 85 

Exceptional differences between the raw and pasteurized milk cheese. 86 

Summary of discussion of scores 87 

The demand for pasteurized-milk cheese 88 

Opinions of purchasers 89 

The extra cost of making pasteurized-milk cheese 89 

Further trials of the new process in cheese factories 90 

Summary 90 

Preliminary and comparative work with the old and new methods 90 

Some advantages from the use of pasteurized milk and hydrochloric acid. . 92 

Outline of the new method 93 



ILLUSTRATIONS. 



PLATES. 

PsEe. 

Plate I. Outfit used in testing milk for acidity (Manns'sacid test) and in testing 

slrongth of hydrochloric acid used in cheese making 32 

IL The continuous disk pasteurizer, and apparatus used in acidulating 

pasteurized milk 32 

IIL The continuous "flash" paaleurizer, and apparatus used in acidulatiii,,' 

pasteurized milk 32 

IV. Transferring acid from full to empty carboy by means of siphon 36 

V. Vat strainer for straining milk into receiving vat 30 

VI. A uniform layer of curd, showing use of curd gauge 48 

TEXT FIGURES. 

Fig. 1. A combined sterilizer, cooler, and incubator for cheese-factory starter.. 43 

2. Method of marking cheese 52 

3. Distribution of total scores of pasteurized and raw milk cheese 78 

4. Distribution of flavor scores of pasteurized and raw milk cheese 78 

5. Distribution of texture scores of pasteurized and raw milk cheese 79 

6. Distribution of total scores of pasteurized and raw milk cheese 81 

7 



THE MANUFACTURE OF CHEESE OF THE CHEDDAR 
TYPE FROM PASTEURIZED MILK. 



INTRODUCTORY. 
THE NEED FOR A NEW METHOD OF CHEESE MAKING. 

Economy of time and labor and ini})roved quality and uniformity 
of the cheese produced make the large cooperative factory mure 
profitable to farmers than the small factory, provided they retam 
the control, if not the complete ownership, of it. There are two 
objections sometimes raised against tlie replacement of four or five 
small cheese factories in a neighborhood by one large, better- 
equijjped, better-manned, and more economical cheese factory, ■ 
namely: First, that by present factory methods cheese makere could 
not make as good cheese from milk gathered over a large territory, 
because it would be longer on the road to the factory and therefore 
would not be so fresh as otherwise; second, farmers object to haul- 
ing milk a great dLstance, even to a good cheese factory. 

The only way to get a large, first-class cheese factory located within 
a short distance of a sufficient milk supply is to centralize the latter — 
that is, to keep as many of the best cows on every farm as the land 
will su])])ort. Until (his is done there will be many factories which 
must th'aw milk from a large area. Some modification of present 
cheese-factory methods is needed by which milk from a large territory 
can be successfully handled. 

The great amount of inferior cheese on the market and the lack of 
uniformity which characterizes the product of the present cheese 
factory of average size is due primarily to the variable quality of the 
milk supply from different farms, especially as to the presence of dirt 
and bacteria, which produce faulty flavors and textures in great 
variety, and to the variable ripeness or acidity of the milk received 
from day to day, dependmg upon the care given to it on the farm, 
its age, etc. 

The immediate effect of these conditions is that cheese makers hi 
their effort to produce cheese of uniform quality from milk of variable 
quality must necessarily use methods which vary from day to day 
and from factory to factory. Under this system each vat of milk 
must be watched carefully at every stage of its manufacture, and the 

9 



10 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

cheese-making process must be hastened, or delayed, or modified 
every day, according to the cheese makers' judgment. The yield of 
cheese also varies from day to day, depending upon the quality of the 
milk and the method used in handling it. 

The ideal conditions for cheese making require an absolutely clean 
and perfect milk supply, and this can not be realized until methods 
of milk production on the farm are vastly improved. In the mean- 
time a process for treating milk daily at the factory so as to bring it 
into practically uniform condition for cheese making purposes is 
needed. Such a process should include means for stopping the 
ripening and the growth of harmful bacteria, etc., in the m'dk as soon 
as it is received at the factory, in order that it may be ripened with a 
clean starter, in a uniform manner, daily. The process should be 
applicable to milk of any degree of ripeness which can properly be 
accepted as fit for cheese making from a sanitary standpoint. When 
mUk is thus brought by a preliminary treatment into uniform condi- 
tion at the factory, both as to acidity and as to bacterial content, 
the present variable and irregular methods of making cheese could 
^probably be replaced by a routine process, operated upon a fixed time 
schedule without variation from day to day. As a result, it is to be 
expected that the uniformity, quality, and yield of cheese would be 
much improved as compared with that obtained by the older methods. 
In many other lines of manufacture in recent years preliminary proc- 
esses have been devised for bringing raw materials into uniform 
condition before they enter the manufacturing process, and improved 
products, increased economies, and larger output and profits have 
resulted. It is desirable that the same general methods of improve- 
ment which have been used with success m other lines be applied also 
to the cheese-making industry. 

FAULTS TO BE CORRECTED IN MILK FOR CHEESE MAKING. 

The defects most commonly met with in milk, which must be cor- 
rected by such a preparatory process as that contemplated, are of 
bacterial origin. A variable content of laciic-acid bacteria causes 
milk when received at the factory to exhibit different degrees of 
acidity and also causes the subsequent development of acid in the 
milk and curd, while in the vat, to go on at varying rates. On 
account of the important influence which acidity has upon the rate 
at which whey is expelled from curd, as pointed out in a previous 
bulletin,^ it may well be said that this is the leading controlling factor 
in the manufacture of American Cheddar cheese. Therefore it is of 
prime importance to secure milk of uniform acidity with which to 

' Sammis, J. L., Suzuki, S. K., and Laabs, F. W. Factors controlling the moisture content of cheese 
curds. U. S. Department of Agriculture, Bureau of Animal Industry, Bulletin 122. Washington, 1910. 
See p. 29. 



NECESSITY FOE PASTEURIZATION. 11 

begin cheese making, and also to provide for subsequent acid de- 
velopment at a practically fixed rate every day in order to avoid the 
present troubles due to irregular acid formation. 

Those bacteria which produce gas or tainted, unclean flavors are 
all too common in milk, and are the cause of much trouble in tlie 
cheese factory. Bacteria which produce diseases such as tuberculosis, 
typhoid fever, diphtheria, dysentery, etc., have often been found in 
milk, although it is difficult to prove that any person ever contracted 
these diseases from eating cheese. These and other bacterial infec- 
tions of raw cream and milk for city trade are usually combated by 
pasteurization; this is true, like^Aise, in butter making, and with skim 
milk when used for feeding stock. It seems reasonable, therefore, 
that any process, such as pasteurization, which will kill the acid, 
taint, gas, and disease-producing organisms in milk would also im- 
prove the quality of the cheese produced therefrom. 

THE NECESSITY FOR THE PASTEURIZATION OF MILK FOR CHEESE 

MAKING. 

In view of the possible presence of tubercle bacilli in market 
cheese, Mohler ' in 190(S recommended the "pasteurization of the 
milk in order to make the cheese perfectly safe." Mohler, Washburn, 
and Doane - prepared and studied cheese from milk to wliich cultures 
of bacillus tuberculosis had been added. They inoculated guinea 
pigs with such cheese at various periods of time after its manufacture 
and found that — 

Advancing cases of generalized tuberciilosis were developed (in guinea pigs) by 
means of inoculation of cheese 220 days old, and that slight tubercular lesions were 
caused by the injection of an emulsion of cheese when 261 days old." 

They add: 

If it is possible to use pasteurized milk iu the manufacture of cheese without injuring 
the product a simple solution of the problem is offered to the cheese manufacturer in 
the process known as pasteurization. 

These authors also give a brief resume of previous work on this 
subject in Europe and America. 

It is evident that the bacillus of tuberculosis not only retains its 
Ufe but also its virulence in cheese for a considerable period of time, 
and that cheese made from raw, unpasteurized milk should therefore 
be considered as a possible carrier of tubercle bacilli. 

There is a strong tendency at the present time to cure American 
cheese more rapidly than in the past, so that it commonly reaches 

'Mohler, John R. Conditions and diseases of the cow injuriously affecting the milk. U. S. Treasury 
Department, PubUc Health and Marine-Hospital Service, Hygienic Laboratory, Bulletin 4L Washing- 
ton, 1908. See p. 495. 

2 MohJer, John R., Washburn, Henry J., and Doane, C. F. The viability of tubercle bacilli in cheese, 
Twenty-sixth Annual Report of the Bureau of Animal Industry, U. S. Department of Agriculture (.1909), 
pp. 187-191. Washington, 1911. 



12 CHEDDAE CHEESE FROM PASTEURIZED MILK. 

the consumer at a less age than four months. It has also been 
shown ' that practically all — 95 to 98 per cent — of the bacteria 
present in milk are retained in the cheese. These facts serve to 
emphasize the desirability of pasteurizing milk for cheese making. 

An ordinance passed by the common council of the city of Chicago 
July 13, 1908, contemplated the pasteurization of milk used for 
cheese making, although at that date no practical methods for 
making American cheese from pasteurized milk had been published. 
The ordinance was as follows: 

Cheese. Be it ordained by the city council of the city of Chicago, * * * 
Section 2. It shall be unlawful to sell any such cheese in the city of Chicago unless 
there be stamped on the package in plainly legible letters of not less than one-eighth 
inch type: "Made of milk (or cream) from cows free from tuberculosis as shown by 
tuberculin test," or "made from milk (or cream) pasteurized according to the rules 
and regulations of the department of health of the city of Chicago * * *. " 

Sec. 4. This ordinance shall be in full force and effect from and after January 1, 
1909. 

AMOUNT OF HEAT NECESSARY TO DESTROY VARIOUS BACTERIA. 

The question as to what temperature of pasteurization will kill 
disease-producing bacteria in milk is of interest to the consumer and 
all connected with the business. 

The thermal death point of various pathogenic organisms is 
already well known. Rosenau states as a result of his work and that 
of others that "milk heated to 60° C. (140° F.) and maintained at 
that temperature for two minutes will kill the typhoid bacillus." 
The great majority of these organisms are killed by the time the 
temperature reaches 1 or 2 degrees below the point named and few 
survive to 140° F. 

The diphtheria bacillus succumbs at comparatively low tempera- 
tures. Oftentimes it fails to grow after heating to 55° C. (131° F.). 
Some occasionally survive until milk reaches 60° C. (140° F.). The 
cholera vibrio is similar to the diphtheria bacillus so far as its thermal 
death point is concerned. The dysentery bacillus is somewhat more 
resistant to heat than the typhoid bacillus. It sometimes withstands 
heating at 60° C. (140° F.) for live minutes. All, however, are 
kiUed when held at this temperature for ten minutes.^ 

In 1904 Russell and Hastings ^ found that the tubercle bacillus is 
killed by heating at 71° C. (160° F.) for one minute. 

From the foregoing it is clear that pasteurization at 71° C. (160° F.) 
for one minute, and in most cases for a shorter period, is effective in 

' Sammis, J. L., Suzuki, S. K., and Laabs, F. W. Factors controlling the moisture content of cheese 
curds. U. S. Department of Agriculture, Bureau of Animal Industry, Bulletin 122. Washington, 1910. 
See p. 29. 

2 Rosenau, Milton J. The thermal death points of pathogenic microorganisms in milk. U. S. Treasury 
Department, Public Health and Marine-Hospital Service, Hygienic Laboratory, Bulletin 56, pp. 683-686. 
Washington, 1909. 

3 Russell, H. L., and Hastings, E. G. Eflect of short periods of exposure to heat on tubercle bacilli In 
milk. Wisconsin Agricultural Experiment Station, Twenty-first Annual Report (1904), pp. 178-192. Mad- 
ison, 1904. See p. 185. 



PREVIOUS ATTEMPTS WITH PASTEURIZED MILK. 13 

destroying pathogenic bacteria in milk and preventing their entrance 
into cheese. 

Babcock and Russell/ from their experiments upon the thermal 
destruction of galactase, state that "lieating (lie enzym solutions for 
10 minutes at 76° C. (169° F.) suffices to destroy tlie dig(>stive fer- 
ment galactase, and even at 71° C. (160° F.), for tlie same exposure, 
its action was materially reduced." It seems hkely, therefore, that 
an exposure to 160° F. for 1 minute or less in the continuous pas- 
teurizer would not greatly weaken the action of this enzym in milk 
for cheese-making purposes.^ 

Much less attention has been paid by bacteriologists to the tiiermal 
death point of those bacteria in nu'lk wluch produc(^ gas and tainted 
flavors in cheese. , Moore and Ward ^ have described a gas-producing 
bacillus isolated from milk and from gassy cheese which "is destroyed 
in freshly inocidated small tubes of bouillon when exposed to a tem- 
perature of 60° C. (140° F.) for 10 minutes in a closed water bath." 

It is to be lioped that in the future investigators will determine 
also the minimum temperature required to kill various species of 
milk bacteria with an exposure of 1 mmute or less as in the continuous 
pasteurizer. 

PREVIOUS ATTEMPTS TO MAKE CHEESE FROM PASTEURIZED MILK. 

The possibility of ninking American chees<> from p;isteurized milk 
luis been studied at sevcn'al experiment stations and i^lsc where. TJie 
two difficulties met with are: 

First, the fact, long known, tliat heated milk coagulates slowly 
with rennet, giving a loose, spongy curd wliicli is not suital)le for 
cheese making because it is too fragile to be handled. 

Second, pasteurization causes curd to ex])el wh<'y more slowly 
than otherwise. 

In order to restore the coagulabdity with rennet to pasteurized 
milk, Klein and Kirsten '' in 1S9S added calcium chlorid and a bac- 
terial starter and were able to obtain fairly good limburger and otlier 
soft cheeses. Tlie}^ used for 100 kilograms of skim milk 100 to 125 
cubic centimeters of .a solution containing in 100 c. c. 40 grains of 
calcium chlorid, corresponding to 20 grams calcium oxid. 

' Babcock, S. M., Russell, H. L., and Vivian, Alfred. Properties of galactase: A digestive ferment of 
milk. Wisconsin Agricultural -Experiment Station, Fifteenth Annual Report (1898), pp. 77-86. Madison, 
1898. See p. 82. 

2 Kastle, Joseph H., and Roberts, Norman. The chemistry of milk. IT. S. Treasury Department, 
Public Health and Marine-Hospilal Service, Hygienic Laboratory, Bulletin 56, pp. 315-417. Washington, 
1909. 

' Moore, V. A ., and Ward, A. R. An inquiry concerning the source of gas and tiiint producing bacteria 
in cheese curd. New York (Cornell) Agricultural Experiment Station, Bulletiji 15S. Ithaca, 1899. See 
p. 236. 

< Klein and Kirsten, A. Versuche, befreffend die Wiederherstellung der Verkasumgsfiihigkeit erliitzter 
Milch durch Chlorcalciumzusatz. Milch-Zeitung, vol. 27, no. 50, pp. 785-787, Dec. 10; no.51, pp. SO.3-805, 
Dec. 17. Leipsic, 1891?. See also Fleischmann, W. Lehrbuch der Milchwirtschaft. 4th edition. Leipsic, 
1908. See pp. 304, 305. 



14 CnEDDAR CHEESE FROM PASTEURIZED MILK. 

In Denmark a kind of cheese is made from pasteurized skim milk 
to which about 10 per cent of buttermilk is added so as to bring the 
acidity up to about 0.21 per cent just before adding rennet.^ 

In 1907 Dean - stated as a result of experiments in the use of cal- 
cium chlorid with pasteurized milk for cheese making "the coag- 
ulum was of a soft, weak nature and the cheese tended to be soft and 
porous." He also added 1^ to 3 per cent of bacterial starters to 
milk pasteurized at 180° F. and ripened some time before adding 
rennet. The rennet coagulated the milk, but the curd was weak in 
body. He noted an increased yield of cheese, but the cheese tended 
to be open and weak in body and texture. He adds: 

On the whole the results are not very satisfactory and we shall require more light 
on the subject of making pasteurized milk cheese before we could recommend the 
method to Canadian cheese makers. 

In 1910 C. A. Publow ^ mentioned briefly some experiments in 
making cheese from pasteurized milk, adding to each 100 pounds of 
milk 2 cubic centimeters of a 25 per cent solution of calcium chlorid 
and 2 or 3 pounds of bacterial starter. The details of the method 
and the opinions of cheese judges other than the author respecting 
the product are not pubhshed. At this station in previous years 
efforts have been made to obtain good American cheese from pas- 
teurized milk ^^'ith the aid of calcium chlorid, but without success. 

DIFFICULTIES MET IN MAKING CHEESE FROM PASTEURIZED MILK. 

Pasteurization of milk prevents or greatly delays subsequent 
coagulation with rennet. The curd from such miUv when finally 
cut into cubes expels moisture with much greater difficulty than a 
raw-milk curd, probably because of some chemical change produced 
in the casein by the heat of pasteurization. Rapid acid formation 
by bacterial action which occurs in raw milk and raw-milk curds 
does not occur in the pasteurized material. The presence of a mod- 
erate amount of lactic acid in raw-milk curds greatly hastens the 
separation of whey from the curd, and the lack of acid development 
in pasteurized-milk curds is another condition favoring the retention 
of excessive moisture in the curd and cheese. 

The addition of calcium chlorid to milk which has been pasteurized 
is known to restore in a measure the coagulabihty of the milk with 
rennet, but we have observed, as Publow* points out, that, although 
coagulation begins in about five minutes, "the curd does not become 
firm enough for cutting in the usual time and should not be cut 
before it is firm." Although the addition of calcium chlorid restores 

I Decker, John W. Cheese making. 5th edition. Madison, Wis., 1909. See p. 194. 
»Dean, H. n. Experiments in cheese making. Ontario Agricultural College, Thirty-third Annual 
Report (1907). Toronto, 1908. See p. 120. 
» Publow, Charles A. Fancy cheese in America. Chicago, 1910. See p. 20. 
* Loo. cit. See p. 21. 



DIFFICULTIES OVERCOME BV ACIDULATION. 15 

the coagulability with rennet, it does not correct the acidity and the 
other difficiihies mentioned above as being caused by pasteurization. 
The lack of acidity in such curd might be supplied by adding starter 
to the pasteurized milk and lipening for several hours before startmg 
tlie cheese making, but the resulting loss of time would prohibit this 
practice in factories. Where both starter and calcium chlorid are 
added to milk after pasteurization, as suggested by Publow, and the 
cheese-making process is begun at once without waiting for ripening, 
tlie daily variations in natural acidity of the milk used produce cor- 
responchng variations in the moisture content of the cheese which 
affect its quahty. (See Table 1.) 

What is needed in place nf calcium chlorid for addition to pasteur- 
ized milk is something which will not only restore the coagulabiHty 
with rennet, but which will also bring up the acidity without delay to 
a sufficiently high percentage to induce reasonably rapid and com- 
plete soj)aration of whey from curd. A uniform acidity is necessary 
daily so as to avoid daily variations in moisture content of cheese. 

DIFFICULTIES OVERCOME BY ACIDULATION OF PASTEURIZED MILK. 

The substance which has been found to meet all of thv, foregoing 
r(M|uirements and which appears to be unobjectionable from all stand- 
points is hydrochloric acid. While it might appear im})racticable 
at first glance to acidulate milk in large quantities daily at a factory, 
yet u]M)n trial this is found to be (Mitirely practicable; and it has now 
been (lon(> almost daily for nearly three years, without any trouble 
arising from coagulation of the milk with acid at any time. 

In Table 1 is shown the moisture content of green cheese obtained 
on 12 days from pasteurized milk by the use of calcium chlorid 
in the proportions suggested by Publow (see p. 14) and by the 
use of hydrochloric acid, using always sufficient acid to raise the 
acidity of the milk to 0.2.5 ])er cent calculated as lactic acid. The 
milk used in the two vats was taken from the same receiving vat 
full of milk, after thorough mixing. It was all pasteurized alike 
and one-half was then treated with calcium chlorid and the other 
with hydrochloric acid. These were then made up into cheese 
separately and were sampled for moisture at the time the cheeses 
were dressed, after pressing one hour.^ From the table it can be 
seen that whenever the acidity of the milk used was low (0.16 to 0.18 
per cent) the moisture content of the cheese made with calcium 
clilorid was high (40 to 44.45 per cent), and when the acidity was high 
(0.21 to 0.23 per cent) the moisture content was low (38 to 40 per 
cent). But in all cases where hydrochloric acid was added instead 
of calcium chlorid the moisture content of the ctird was 37.5 to 40 
per cent, whether the natural acidity of the milk was high or low. 

» Thfi correctness of this method of sampling cheese for the moisture test is demonstrated in the latter 7 art 
nrthis bulletin, 



16 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



Table 1. — Comparison of moisture content and qvalily of cheese made with calcium 
chlorid and with hydrochloric acid. 





Acidity 
of milk 
when 
pas- 
teur- 
ized. 


How made. 


Moisture 

content of 

dressed 

cheese. 


Score. 


Criticism. 


Date made. 


Fla- 
vor. 


Tex- 
ture. 


Flavor. 


Te.xture. 


1911. 
Aug. 18 

Do 

Aug. 22 

Do 

July 28 

Do 

Aug. 23 

Do 

Aug. 24 

Do 

Aug. 2.5 


Per ct. 
0.165 
.16.5 
.165 
.165 
.17 
.17 
.175 
.175 
.175 
.175 
. 175 
.175 
.185 
.185 
.190 

.190 

.21 

.21 

.21 

.21 

22 
'.22 
.31 

1S7 


Calcium chlorid . . . 
Hydrochloric acid . 
Calcium chlorid... 
Hydrochloric acid. 
Calcium chlorid . . . 
Hydrochloric acid. 
Calcium chlorid . . . 
Hydrochloric acid. 
Calcium chlorid... 
Hydrochloric acid. 
Calcium chlorid.. . 
Hydrochloric acid. 
Calcium chlorid . . . 
Hydrochloric acid. 
Calcium chlorid . . . 

Hydrochloric acid. 
Calcium chlorid . . . 
Hydrochloric acid. 
Calcium chlorid . . . 
Hydrochloric acid. 
Calcium chlorid . . . 
Hydrochloric acid, 
.do 


Per cent. 
42.25 
37.70 
42.35 
38.80 
41.50 
37.70 
44.27 
39.20 
44.27 
39.62 
44.45 
39.02 
42.90 
39.90 
41.50 

39.95 
39.20 
39. 62 
38.70 
38.60 
40.60 
39.95 
39. 05 
37.58 


38 

41i 

40 

41 

38 

4U 

39| 

40J 

37 

41 

m 

4U 
40 
4U 
39 

41i 

41 

41 

39 

41i 

41 

41 


26 

27* 

26 

27J 

24 

28 

25i 

27 

25 

26J 

26* 

28' 

25 

28 

26 

27i 

26 

26i 

26^ 

27 

26i 

27* 


Flat, pungent 

Clean 


Curdv, loose, weak. 
Trifle loose. 


Flat, lacking 

Clean and 0. K... 

Lacks acid 

Trifle acid 

Low, lacking 

Trifle sharp 

Sour-milk flavor . . 

Trifle sharp 

Clean and O.K... 
0. K 


Weak, sticky. 
Trifle weak." 
Wet and sticky. 
Trifle sticky. 
Trifle weak. 

Do. 
Very loose, weak. 
Trifle weak. 
Sticky, loose, short. 


Aug. 11 

Do 


Bitter, lacks acid.. 
O.K 


Coarse, loose. 


Sept.4 

Do 

Aug. 17 

Do 


Sweet, bitter 

.\cid aftertaste 

Tastes sal tv 

do ■ 


Weak, mechanical 

holes. 
Mechanical holes. 
Weak and sticky. 
Loose, sticky. 
Sweet holes. 
Trifle loose. 
Short, sticky. 
Trifle short. 


Aug. 16 

Do 

Aug. 2S 

Do 


Vinegar flavor 

Clean and 0. K... 

Trifle bitter 

..do 


Aug. 7 

Aug 10 






....do 




Aug 21 '?i-i 


do 

Calcium chlorid . . . 
Hydrochloric acid. 


38.67 










-Average . . . 














42.00 
38.95 


39.45 
41.23 


25.73 
27.36 




Do 











From the above table it is evident that when milk is acidulated w4th 
hydrochloric acid after pasteurization, as in the new method, the 
moisture content of the green cheese is not affected by the ripeness of the 
milk before pasteurization and is quite constant betw^een 37.5 and 40 
per cent. This advantage does not attend the use of calcium chlorid. 
The daily variations of moisture content shown in column 4, which 
are between 37.5 and 40 per cent, are doubtless due to causes other 
than acidity, and did not noticeably affect the rjuality of the cheese. 
The scores and criticisms show that the cheese made with calcium 
chlorid was neither as uniform nor as good m cjuality as that made 
with hydrochloric acid. 

The addition of hydrochloric or lactic acid to cream to raise its 
acidity without delay, preparatory to churning, was attempted by 
Babcock in 1888.^ The addition of a commercial acid to raw milk 
to raise its acidity without waitmg for bacterial action w^as suggested 
to the waiter in 1905 by Dr. S. M. Babcock, chief chemist of the 
Wisconsin Experiment ^Station, and during the years 1905-6 the 
effort was made, folio wmg the suggestion of Dr. Babcock, to avoid 
the necessity for ripening milk for cheese making at the factory and 

1 Babcock, S. M. Churning tests. Wisconsin .Agricultural Experiment Station, Fifth .Annual Report, 
1888, p. 111-121. Madison, 1888. See p. 118. See also patent granted to .\Iiiller, Milch-zeitung, vol. 23, no. 
19, p. 301, Bremen, May 12, 1894; also notes on this subject in same volume, pp. 425, 464, 701, 750. 



DIFFICULTIES OVERCOME BY ACIDULATION. 



17 



to substitutp for such ripoiiing the addition of a oonimorcial arid to 
the milk as soon as it was received. Immediately after acidulating 
the milk it was heated to 86° and rennet was added and the process 
completed in the usual maimer. These exjieriments showed conclu- 
sively that a commercial acid such as hydrochloric acid can be added to 
milk without in any way damaging the quality of the cheese obtained. 
However, the (juality of cheese obtained from ovempe or tainted 
milk was not im})roved by the use of the acid, and it was concluded 
that acidulation alone does not offer sufficient advantages to warrant 
its recommendation to cheese makers. The addition of acids to 
pasteurized milk for cheese making was begun by the writer in 1907. 

Pasteurization and acidulation of milk appear to be complementary 
processes, each supplying what the other lacks and together forming 
the basis of an improved method of chee,se making. 

Since the use of calcium chlorid in pasteurized-milk cheese will not 
be referred to again in this paper, two other points will be mentioned 
here in which the use of hydrochloric acid is more advantageous. 
These are: First, that the hydrochloric acid curds always begm to 
thicken 6^ to 7 minutes after rennet is added, while with calcium 
chlorid the first visibl{> coagulation occurs earlier if the milk used is 
very ripe and later if the milk is sweet, thus varying from day to day, 
as shown in Table 2. Second, the percentage of fat lost in the whey is 
on the average about 0.14 per cent greater in the method using cal- 
cium chlorid than when hydrochloric acid is used, as also shown in 
Table 2. This is probably because calcium chlorid curds are always 
more mushy and easier to break up in stirring than curds made with 
hydrochloric acid. The latter are really superior in this res])ect to 
curds obtained by the regular factory methods. 

I'able 2.— Comparison of calcium chlorid with hydrochloric acid as to their effects on cheese 

made icith pasteurized milk. 



Date. 


Time required for 
vi.sihlp, coagula- 
tion after adciinp; 
rennet. 


Per cent of fat in 
whey at time of 
drawing whey 
and ma 1 1 i n g 
curd. 


Acidity 
of milk 
used. 


Calcium 
chlorid. 


Hydro- 
chloric 
acid. 


Calcium 
chlorid. 


Hydro- 
chloric 
acid. 


1911. 
July 28 
Aup. 11 
16 
17 
18 
22 
23 
24 
25 
28 

Average.. 


Minutes. 
14 
15 

6 

4 

14 
Hi 
18 
18 
16 

6i 


Minutes. 
7 

7 
7 
7 

7 
7 

7 
7 
7 


Per cent. 
0.23 
.35 
.16 
.21 
.32 
..32 
.-.iO 
.42 
.38 
.17 


Per cent. 
0.13 
.14 
.12 
.14 
.19 
.18 
.20 
.20 
.16 
.13 


Per cent. 
0.17 
.185 
.21 
.21 
.165 
.165 
.175 
.175 
.175 
.22 






.295 


.159 

















79994°— Bull. 165—13- 



18 



CHEDDAE CHEESE FROM PASTEURIZED MILK. 



THE PASTEURIZATION PROCESS. 
PASTEURIZATION IN A DISCONTINUOUS OR "HELD" PASTEURIZER. 

In May, 1907, one day's milk supply was divided in two portions, 
one of which was made up by the regular method and the other was 
pasteurized for 18 mmutes at 160° F. and acidulated with hydro- 
chloric acid. The pasteurized vat gave the best-flavored cheese after 
curing, though it was inferior in texture to the other. On March 12 
and 27, 1908, milk pasteurized at 140° for 20 minutes and then acidu- 
lated gave such good cheese that a systematic study of the combined 
process of pasteurization and acidulation was begun in July, 1908. 
Cheese was made from milk pasteurized at 140° F. for 20 minutes, 
either in a Potts pasteurizer or in the cheese vat, by running first 
steam and then cold water into the jacket. At the same time part of 
the milk supply after mixing and dividing was used for making cheese 
by the regular methods. The scores given to the two lots of cheese 
thus obtained are shown below: 

Table 3. — Comparison of flavor and texture of cheese made from raw m,ilk andjrom milk 
pasteurized at 140° F. for 20 minutes. 





Pasteurized cheese. 


Regular make. | 


Date 
made. 




















Flavor. 


Texture. 


Flavor. 


Texture. 


1908. 










Julv 16 


3S.3 


26.2 


36.2 


27.8 


17 


40.0 


27.0 


38.5 


26.25 


IS 


41.7 


27.5 


39.25 


27.0 


20 


40.8 


26.3 


37.3 


26. 75 


21 


41.2 


26.0 


41.2 


26.2 


22 


41.3 


26.8 


38.0 


26.75 


23^ 


40.8 


26.7 


39.5 


26.5 


24 


41.0 


27.25 


38.3 


26.25 


31 
Average.. 


40.25 


26.25 


36.5 


26.5 


40.59 


27.00 


38.30 


26.66 



The scoring was done by J. W. Moore and F. W. Laabs. In every 
case but one the pasteurized cheese had better flavor and there was 
little difl'erence in texture between the two lots. 

CONTINUOUS AND "hELD" PASTEURIZATION COMPARED. 

On account of the large volume of milk which must be handled 
daily in a cheese factory, and the greater expense involved in providing 
arrangements of sufficient capacity for heating and cooling 5,000 to 
7,000 pounds of milk at one time as compared with the small cost of 
a continuous pasteurizer, most of the later work was done with 
continuous pasteurizers. These can be used for handling any 
required volume of milk, a larger quantity simply necessitating a 



COMPARISON OF CONTINUOUS AND " HELD " PASTEURIZATION. 19 

longei tini(> for ninniu<j;. A( tho pros«Mit time thoy arc believed 
preferable for cheese-factor}' use over any form of intermittent ])as- 
teurizer yet devised. Good results had be(Mi obtained by pasteuri- 
zation at 140° for 20 minutes, but since continuous })asteurization 
'seemed th(> more ])ractical factory metliod, it was determined to lise 
both methods in c<)m])aris()n on the sam(> nnlk for several (hiys. On 
eio;lit days, between »Iuly 16 and 24, 190S, half of the milk was pas- 
teurized at 140° for 20 minut(^s and the otlier half at either 150°, 160°, 
or 170° in the continuous machhie. The elTectiveness of the two 
methods of })asteurization was jmln^ed from the mcrease in acidity 
observed iji the whey within the time from cuttint:; curd to drawing 
whey specified in each case. 

Table 4. — Increase of aciditi/ after pasteurization by continuous and by held processes. 



Pate. 


Milk held at 140° 
for 20 minutes. 


Milk pasteurized 
at 150°. • Instan- 
taneous. 


Milk pasteurized 
at 160°. Instan- 
taneous. 


Milk pasteurized 
at 170°. Instan- 
taneous. 


In- 
crease. 


Time. 


In- 
crease. 


Time. 


create. ^ime. 


In- 
crease. 


Time. 
H. m. 


1908. 
July 16 
17 
18 
20 
21 
22 
23 
24 


Per ct. 
0.11 
.068 
.055 
.01 
.02 
.03 
.078 
.018 


n. m. 

2 57 
2 17 
2 17 
2 31 
2 10 
2 21 
2 10 
2 30 


Per ct. 


H. TO. 


Per ct. H. m. 

0. 055 3 

.03 2 59 

.03 1 2 46 


Per ct. 






















0.01 
.01 
.035 
.053 


3 30 
3 30 
3 20 
3 8 




















0.01 


2 40 




1 







From the above it can be seen that where milk is lughiy inociPated 
when raw, as on July 16, 17, 18, and 23, the acidity of the whey rose 
0.05, 0.06, 0.07, and 0.11 per cent in about 2\ hours after pasteur- 
izing at 140° for 20 minutes, while it rose only about half as high in 
3 hours after pasteurizing at 160° or 170° in the continuous machine. 

A further substantial difference between curds from milk pasteur- 
ized on the one hand at 140° for 20 mhiutes and on the other at 160° 
in the continuous machine is that the former curds often become mel- 
low and greased on the surface and leak white whey after milling, in 
this respect resembling some raw-milk curds. Tt was supposed at 
first, from analogy to ordinary factory methods, that the curd which 
became mellow and somewhat greased on the surface and which leaked 
more or less white whey was more likely to turn out well than the 
other, which was supposed to be lacking in acid or acid-forming 
bacteria. The observation was made that a curd from milk pasteur- 
ized at 170° and afterwards treated with 5 per cent starter did not 
become mellow in the least, while curds from the same day's milk 
pasteurized at 140° for 20 minutes and then treated with tliree- 



20 



CHEDDAR CHEESE FEOM PASTEURIZED MILK. 



fourths per cent starter, became very mellow and abundantly greased 
before milling. It was judged unnecessary, thereafter, to wait for 
mellowness or any other evidence of bacterial action or acid develop- 
ment in a pasteurized-milk curd. If a sufficient proportion of starter 
has been added after pasteurization, it is perfectly certain that the 
bacteria are present in the curd, and will take part in the curing on the 
shelf. From this point of view the mellowness which the 140° curds 
occasionally exhibit is to be regarded as objectionable and as evidence 
of lack of uniformity between different days' make, and smce this 
never occurs with nidk pasteurized at 160° in the continuous machine 
the latter appears preferable. 

The cause for the greater increase of acidity in whey after cutting 
curd from mOk pasteurized at 140° for 20 minutes, as shown above, 
is no doubt the fact that the milk thus j^asteurized contained more 
living, active bacteria than that pasteurized in the continuous 
machine. Samples were taken for bacteriological count in every 
case immediately after pasteurizing, and then three-fourths per 
cent of starter was added to each vat, followed immediately by 
rennet as soon as the vat could be heated. Bacterial counts were 
made on these samples by Mr. L. D, Bushnell, bacteriologist, as 
follows : 

Table. 5. — Number of bacteria per cubic centimeter in raw and pasteurized milk. 



Date. 


Raw milk. 


Pasteurized milk. 


At 140° for 20 
minutes. 


In continuous machine. 


1908. 
July 17 
18 
20 
21 
22 
23 
24 


Number per c. c. 
102,000,000 

72, 000, 000 
119,000,000 

30,000,000 
173,000,000 
360,000,000 

65,000,000 


Number per c.c. 

2,206,000 

2,620,000 

262, 000 

33,000 

320,000 

15,320,000 

62,000 


Number per c. c. 

652, 000 

1,960,000 

200,000 

9,200 

38,000 

1,300,000 

1,100,000 


"F. 
160 
160 
170 
170 
170 
170 
150 



SELECTION OF BEST TEMPERATLTKE FOR PASTEURIZATION IN THE 
CONTINUOUS MACHINE. 



The temperature selected should be high enough to insure that 
the ripening of the milk shall be uniformly checked daily, regardless 
of the bacterial content of the milk used, and it should not be so 
high as to injure the quality of the cheese. Tests were made as 
follows: On several days the milk supply after mixing was divided 
into four lots, one of which was made up by regular methods, the 
others were pasteurized at 140°, 150°, and 160° and made up in 
separate vats. The cheese after curing was examined by several 



BEST TEMPERATURE FOR PASTEURIZATION. 



21 



expert cheese judges, including Messrs. U. S. Baer, Robert AIcAdam, 
H. J. Noyes, F. W. Laabs, and Gottlieb Marty, whose scores are 
given in Table 6 : 

Table 6. — Quality of cheese made from raw milk and from milk pasteurized at different 
temperatures in the continuous-disk machine. 



Date. 






Pasteurized at — 




140° F. 


150° F. 


160° F. 


Flavor. 


Tex- 
ture. 


Flavor. 


Tex- 
ture. 


Flavor. 


Tex- 
ture. 


Flavor. 


Tex- 
ture. 


1908. 
July 14 
15 
IG 
17 
20 
21 
22 
15 

16 

17 

20 

21 

22 
23 
24 






40.0 
40.5 
38.0 
38.0 
40.0 
41.0 
37.0 


28.5 
28.5 
28.0 
28.5 
28.5 
28.5 
28.0 


41.5 
41.0 
40.0 
41.0 
41.0 
41.0 
38.0 


28.5 
29.0 
29.0 
29.0 
28.5 
28.5 
28.0 


43.0 
41.0 
41.0 
42.0 
42.0 
41.5 
39.0 
41.0 
44.0 
42.0 
40.0 
44.0 
41.5 
38.0 
44.5 
43.0 
40.5 
44.0 
41.0 
40.0 
40.0 
44.0 
37.0 
40.0 
35.0 
43.0 
40.0 
43.5 
36.0 


28.5 
29.0 
29.0 
29.0 
29.0 
29.0 
27.5 
27.5 
28.0 
28.0 
27.0 
28.0 
28.5 
23.0 
29.5 
29.0 
28.0 
29.0 
28.0 
28.0 
27.0 
29.0 
29.5 
25.0 
25.5 
27.0 
28.0 
28.5 
26.0 


40.0 
30.0 
36.0 
38.0 
39.0 
35.0 
38.0 
40.0 
40.0 
38.0 
38.0 
30.0 
37.0 
40.0 
35.0 
37.0 
42. 
33. 
30. 
37.0 
39.0 
36.0 
42.0 
37.0 
44.0 
36.0 
43.0 
32.0 


28.5 
27.0 
28.0 
28.5 
29.0 
28.0 
27.0 
26.0 
26.0 
26.0 
24.0 
27.0 
26.0 
26.0 
26.5 
26.0 
27.0 
28.0 
28.0 
25.0 
26.0 
28.0 
28.0 
27.0 
26.0 
27.0 
28.0 
28.0 



















































































































































































In nearly every case the 100° pasteurized-milk cheeses were 
cleaner in flavor and scored higher than the check, and in every 
case they scored higher than the cheeses pasteurized at 140° and 150°. 
The difi'erent judges scored the cheese at difl'erent ages, which will 
account for the wide variation of some scores. Bacterial counts 
made by Mr. W. H. Wright* show that pasteurization at 160° is 
more effective than at lower temperatures. This is well illustrated 
in Table 7. 

'Unpublished work by W. H. Wright, instructor in agricultural bacteriology, Uiiiversity of Wisconsin. 



oo 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



Table 7 .^Bacterial content of milk pasteurized at different temperatures in the continuous- 
disk machine. 



Date. 


Bacteria per cubic centimeter. 


Raw milk. 


Milk pasteurized at— 


140° F. 


150° F. 


160° F. 


1909. 
July 22 
23 
24 




6,080,000 600,000 


50,000 
60,000 
23,000 


423, 000, 000 
11,600,000 


5,800,000 
1,540,000 


600, 000 
139,000 



That the use of 160° for pasteurization is high enough to kill most 
of the bacteria in milk, so as to meet requirements such as tliose of 
the Cliicago ordinance previously referred to on ])age 12, is shown in 
Table 8 by the followmg bacterial counts made by Mr. Alfred Larson 
in 1909: 



Table 8. 



'Bacterial cnnient of milk before and after, pasteurization in the continuous- 
disk machine at 160° F. 



Date. 


Bacteria per cubic centimeter. 


Decrease. 








Raw milk. 


Pasteurized 
milk. 




1909. 






Per cent. 


Aug. 1" 


161,600,000 


223,350 


99.8 


18 


43,300,000 


1,275,000 


97. 


19 


57,600,000 


211,000 


99.6 


20 


16,560,000 


252, 160 


98.5 


21 


20, 938, 000 


40,960 


99.8 


22 


15,548,000 


420, 250 


97.0 


24 


89,750,000 


544,250 


99.0 


26 


44,075,000 


86, 120 


99.8 


27 


76,000,000 


30, 450 


99.9 


28 


78,825,000 


166, 400 


99.8 


31 


148,200,000 


77,560 


99.9 


Sept. 1 


25,836,000 


9,670 


99.9 


2 


51,650,000 


52,125 


99.9 


14 


27,150,000 


29, 2.50 


99. 9 


16 


77,6.50,000 


341,600 


99. 6 


17 


38,900,000 


136,350 


99.6 


IS 


124,700,000 


159,880 


99.8 


19 


00,280,000 


287, 500 


99.5 


21 


185,000,000 


477,600 


99.0 


22 


63,500,000 


263, 200 


99.7 


23 


45,525,000 


142,300 


99.7 


28 


18,376,000 


202,600 


98. 8 


29 


13,660,000 


31,000 


99.7 


30 


980,000 


14,580 


98.5 


1910. 








July a 


6,500,000 


27, 000 


99.6 


12 


1,600,000 


25,000 


98.5 


13 


5,250,000 


17,200 


99.7 


14 


4,700,000 


36,000 


99.3 


15 


10, 000, 0(X) 


28,700 


99.7 


20 


5,350,000 


21,000 


99.6 


Sept. 19 


2,525,000 


30,000 


98.8 



OBJECTIONS TO HIGH TEMPERATURES FOR PASTEURIZATION. 



23 



Similar doterniiiiations were made by Aliss A. C. Evans upon milk 
]>asteurized in the continuous "flash" macliine in 1910. They are 
shown in Table 9: 

Table 9. — Bacterial content of milk before and after pasteurization in the continuous 
' 'flash' ' machine at 160° F. 





Number of bacteria per cubic 






centimeter. 




Date. 




Killed by 






pasteuriza- 




Raw milk. 


Pa.steurized 
milk. 


tion. 


1910. 






Per cent. 


Aug. 3 


7, 950, 000 


4,700 


99.95 


4 


4,250,000 


15,300 


99.65 


5 


9,750,0<X) 


142,000 


98. 45 


9 


1,500,000 


4,850 


99.68 


11 


0, 450, 000 


11,250 


99.83 


15 


2, 850, 000 


43,000 


98.47 


10 


1,017,500 


12,725 


98.75 


17 


38, 000, 000 


700 


99.99 


18 


4, 500, 000 


0,000 


99.87 


19 


3,750,000 


5,500 


99.80 


24 


18,1.50,000 


13,800 


99.93 


25 


14,000,000 


0,500 


99. 96 


30 


47, 300, 000 


10,200 


99. 97 


Sept. 1 


2,150,00<J 


12,000 


99.44 


7 


5, 650, 000 


27,000 


99.53 


8 


8,800,000 


63,000 


99.29 


9 


2,800,000 


5, .500 


99.80 


12 


10, 200, 000 


21,200 


99.73 


IS 


2,120,000 


18,500 


99. 13 


l(i 


18,000,000 


5, 700 


99.97 


19 


2,525,000 


4,300 


99.83 


21 


1,700,000 


11,000 


99. 35 


•a 


9,000,(K)0 


30,000 


99.07 


20 


11,200,000 


28, 000 


99.75 



OBJECTIONS TO HIGHER TEMPERATURES THAN 1G0°-165° F. FOR 

PASTEIRIZATIOX. 

Cheese made by tlie new process from milk pasteurized at 160° has 
always a clean, mild flavor wliich suits practically all markets, and 
wiU please any consumer wlio likes a mild-flavored cheese. Those 
who arc accustomed to and i)refer very old high-flavored cheese 
wt)uld not be suited, but estimates by l(>atHng cheese dealers indicate 
that the proportion of consumers preferring the liigh-flavored cheese 
is very smaD. Most of the cheese sold to-day is only a few wa^eks 
old, because the dealers geiieraUy avoid long storage, preferring quick 
sales and immediate profits. This makes it practically impossible 
for most consumers to develop a taste for any but the new mild 
cheese sold in most markets. The steady sales of pasteurized-milk 
cheese during the past two years indicate that the flavor of the 160° 
pasteurized product is satisfactory for filhng regular orders. Indeed, 
it is an open question whether most of the "liigh snappy" flavor 
often observed in old cheese is not due to the long-continued, slow 
development of those same taints and oflp flavors from unclean milk 
wliich we recognize as objectionable when they develop rapidly. 



24 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



The use of liigher temperatures than 160° for pasteurization was 
tried on several da^s, with the result that the flavor production in 
the cheese was practically prevented and the texture was inferior. 
The scores given to these cheeses are tabulated below: 

Table 10. — Quality of cheese from milk pasteurized at different temperatures in the 

continuous-disk machine. 





Pasteurized at 


Pasteurized at 


Pasteurized at 




160° F. 


170° F. 


180* F. 


Date 
made. 








Flavor. 


Texture. 


Flavor. 


Texture. 


Flavor. 


Texture. 


1909. 














Oct. 12 


40 


29 


3S 


27 


35 


15 


13 


40 


29 


39 


28 


35 


15 


14 


40 


28i 


38 


27 


35 


15 



The scoring was done by Mr. F. W. Laabs. The 180° cheeses have 
no Cheddar flavor, but taste hke first-class cottage cheese. They 
are so crumbly and short that it is impossible to draw a sohd phig. 
They keep well, and it is possible that a good trade might be built 
by the sale of tliis product under some such name as "pressed cottage 
cheese." In all cases the use of 160° for pasteurizing milk gave better 
cheese than higher temperatures. 

Three reasons have been suggested why the milk pasteurized at 
180° gives flavorless cheese: 

First. If bacteria are the essential cause of flavor production, it 
would appear hkely that the necessary kinds of milk bacteria are 
destroyed by the high temperature of pasteurization. 

Second. If milk enzyms such as galactase are the essential cause 
of flavor production, these enzyms are perhaps destroyed by the use 
of 180°. 

Third. It may be that the casein or otlier native milk constituent 
which in normal cheese undergoes cleavage, forming the flavor-giving 
substances present in ripened cheese, is changed chemically either in 
composition or as to constitution by the heating to 180°, so that upon 
cleavage by bacteria, enzyms, acids, or other agencies it yields differ- 
ent cleavage products, lacking the flavor, etc., which characterize 
normal cheese. 

In attempting to test the first of these possible explanations a 
variety of substances have been added as starters to milk after pas- 
teurizing at 180° or other high temperatures in order if possible to 
supply the bacteria or enzym needed for normal curing and flavor 
production. Among the special starters so used were pure cultures 
of various bacteria; raw milk up to 20 per cent of the vat contents; 
cultures of bacteria isolated from milk and cheese capable of develop- 



EFFECT OF PASTEURIZATION ON CHEESE CURD. 



25 



ing 1.6 per cent or more lactic acid in milk (described by Hastings'); 
cheese of various ages rubbed to creamy consistency with milk and 
added in different proportions through a hair sieve to the pasteurized 
milk in the vat; cultures made by adding cheese in this maimer to 
milk and incubating overnight before adding to the cheese vat. All 
of tliese materials were added to milk which had been pasteurized at 
high temperatures u]) to 180°, and cheese was made therefrom; but 
in no case was it possible to get a normal flavor development in the 
resulting cheese. 

The lack of flavor ])roduction under these circumstances, where 
many kinds of bacteria and starters were added to the ])asteurized 
milk, seems to indicate that the casein, etc., in milk thus treated is 
incajjable of cleavage into the flavor-giving substances; in other 
words, tiiat the casein, etc., is changed chemically by the heat of ])as- 
teurization. There is additional evidence that such a change occurs. 

EFFECT OF PASTEURIZATION ON THE PROPERTIES OF CHEESE CURD. 

A series of cheese curds made from milk pasteurized at 160°, 170°, 
180°, or higher temperatures show a regular gradation of certain char- 
acteristics. The higher the temperature of })asteurization tJie more 
tenaciously the curd retains moisture and the more difficult it is to 
ex])el the whey by ordinary means. Tjiis is shown in the foUowing 
ex])eriment: The milk in the receiving vat each morning was thor- 
oughly mix(Hl and then divided into three ])ortions which were run 
through the ])asteurizer at different temperatures and made up into 
cheese in different vats. Three-fourths per cent of starter was added 
to each vat and the milk and curds were handled in all respects as 
nearly alike as possible, the only difference being in the temperature 
of pasteurization. The curds in separate hoo])s were pressed in the 
same press, and the next morning moisture tests were made on each. 
This entire work was repeated on several days. The results are 
shown in Table 11. 

Table 11. — Moisture content of green cheese made from milk pasteurized at dij/'erent tem- 
peratures in the continuous-disk pasteurizer. 



Date. 


Milk pasteurized at— 


160° F. 


170" F. 


180° F. 


1909. 
Oct. 12 
13 
14 


Per cent. 
38.4 
37.0 
39.0 


Per cent. 
42.2 
39.9 
40.7 


Per cent, 
46.6 
43.5 
45.5 



' Hastings, E. G., Hammer, B. W., and Hoffman, C. Studies on the bacterial and leucocyte content of 
milk. Wisconsin Agricultural Experiment Station, Researcli Bulletin 6. Madison, June, 19U9. 



26 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



Each per cent given is the average of two closely agreeing dupli- 
cates. It is seen that in every case the higher temperatures of pas- 
teurization cause higher moisture content in the green cheese. These 
curds were all cut with a three-eighths-inch knife and heated to 104° 
in the whey. 

Even when a 180° curd was cut with one-fourth inch curd knives 
and a 160° curd with three-eighths inch knives, the moisture content 
in the former remained higher, as is shown in the following experiment : 

Table 12. — Moisture content, of curds madefrom milk pasteurized nt different temperatures 
in the continuous-disk pasteurizer and cut with knives of different sizes. 



Milk pasteurized at 1G(J° F. 


Milk pasteurized at 
180° F. 


Time after cutting 
curd. 


Cut into 
f-ineh 
cubes. 


Cut into 
|-inch 
cubes. 


Cut into 
J-ineh 
cubes. 


//. TO. 

1 


Per cent. 
t)7. b 
60.1 
47.2 
43.3 
42.2 
41.4 


Per cent. 
70.0 
63.9 
52.4 
47.2 
45.9 
45.1 


Per cent. 
66.5 
61.0 
50.6 
46.0 
44.6 
43.9 


2 Drew whey... 
2 30 


3 30 Milled curd... 

4 .30 Salted curd... 
4 50 Hooped curd. 



Each per cent in the tahle is the average of two closeh' agreeing 
moisture determinations. 

It is unquestionably true that pasteurized-milk curds retain mois- 
ture more tenaciously than raw-milk curds, and this effect is more 
nnirked the higher the temperature used in the ])asteurization. It 
therefore follows that the higher the temperature used in the })asteur- 
izer the greater w411 be the weight of cheese obtained from pasteurized 
milk. The yield ])er hundred pounds of milk weighed before j)asteur- 
ization in each vat on three days is given in Table 13. 



Table 13.- 



Yield of cheese per hundred pounds of 7nilk pasteurized at different tempera- 
tures. 



Date made. 


Temperature of pasteurization. 


160° F. 


170° F. 


180° F. 


1909. 
Oct. 12 
13 
14 


Pounds'. 
12. 28 
12. 10 
11.93 


Pounds. 
13. 42 
12.97 
12.70 


Poimd.'i. 
15. 42 
14.53 
14.44 



It will be shown later that the yield of cheese obtained by pasteur- 
izing at 160° is slightly greater than that obtained from raw milk, so 
that in this res])ect the effect of pasteurization is distinctly noticeable 
even when the lower temperature is used in the ]nisteurizcr. Again, 



EFFECT OF PASTEURIZATIOX ON CHEESE CURD. 27 

among the peculiarities of pasteurized-milk curds is their decreased 
])()wer to coalesce or fuat when on the rack or in the })ress. Tliis 
effect is not noticeable with milk })asteurized at 160° to 165°, but is 
perceptible at 170° and is very marked when the milk was pasteurized 
at 180° or hiuher. The 180° curd cubes when piled on the rack pack 
together like raisins or figs in a box but do not coalesce or unite, and 
by rubbing the finger over the mass at any time the pieces can be 
])ulled a})art. The same effect is noticed when the curd is pressed in 
the hoo]). The ])ieces ])ack together tiglitly but do not unite; and 
at any time (hiring the curing a ])lug drawn with a trier will either 
come out in fragments or will break into })ieces instantly when han- 
dled. Iiist(>ad of milling such a curd, it is merely stirred or shaken 
apart with the hands. 

These two ])eculiarities of pasteurized-milk curds, which can not 
be remedied or avoichnl by any otlier means tlian reducing tlie tem- 
})erature of the ])asteurization,, considered tog(>ther witli the im])os- 
sibility of d(>v(d()])ing Cheddar fhivor after ])asteurization at high 
tem])eratures, a])])ear to indicate tliat the ])asteurization ])roduces 
some de(>])-seate(l cliange in the chejiiical constitutior; of casein. 

Another ])eculiarity of ])asteurize(l milk, that of coagulating with 
rennet oidy with great tlifficulty, need only be jnentioned in this 
connection, l)ecause in the ])roeess of cheese making her(> described 
the addition of Jiydrochloric acid to the })asteurized juilk entirely 
restores the coagulability witli rejuiet, ])ro(lucing a curd in many 
res])ects su])erior to and easier to handle than the curd co3umoidy 
obtained in the r(>gular way from raw milk. 

From what has been said it will be seen that the use of 160° to 165° 
for ])asteurization offers many jiractical advantages. It is sufficiently 
high to check elfectually the further ri])ening of the milk during the 
next few hours, while the use of 150° is not high enough for this ])ur- 
])ose. Furtherii.ore, 160° gives cheese of cleaner f-Iavor than 140° or 
150° (no doubt by more effectual destruction of taint-producing 
bacteria) or than raw milk, as shown in Ta})le 6. It may be mentioned 
also that over 99 ])er cent of the total bacterial content of the milk is 
destroyed by use of 160°, as shown in Tables 8 and 9. The 160° is 
])referred to 170° or 180° because tlie cheese obtained by the use of 
160° is more nearly like the best American cheese in inoisture content 
(see Table 11) and in texture and flavor. (See Table 10.) 

So far as it is possible to say at the present time, the use of 160° is 
sufficient to kill most probably 99 ])er cent of the gas and taint- 
forming bacteria in milk. It can not' be claimed that they are all 
killed, because it is true that when very unclean milk is handled by 
this process the cheese sometimes shows slight traces of unclean 
flavors, though not enough to affect the market value. While gas 
and pin lioles have often been seen during the seasons of 1909, 1910, 



28 CHEDDAR CHEESE FROM PASTEURIZED MILK, 

and 1911 in cheese made by regular methods at this factory, no gas 
whatever was seen in any curd or cheese mad& during 1909 or 1911, 
and the gassy cheese obtained, nine days in succession, in 1910 was 
demonstrated to be due to the use by mistake of a gassy starter which 
was added to the milk after pasteurization. The fault arose at that 
time from the inefficient means then at hand for preparing and heat- 
ing milk for propagation of the starter. An improved steam sterilizer 
was at once set up for this purpose, which prevented all further diffi- 
culty of this sort during the past two years. 

The temperature finally selected as most completely securing the 
advantages and avoiding the disadvantages of pasteurization for 
cheese makmg is 160° to 165° F. In practice the pasteurizer is set 
running at 163° and held there as closely as possible. 

THE DIFFERENT TYPES OF CONTINUOUS PASTEURIZERS USED. 

Two different pasteurizers were used in this work %vith entire 
success, being apparently e(|ually effective in producing the desired 
results at 160° to 165°. Tliese were a disk machine of 2,000 pounds 
per hour capacity and a "flash" machine of 1,200 ])ounds capacity 
per hour. (See Pis. II and III.) The choice between these two types 
of pasteurizing machines for use in this process a])pears to depend 
upon their relative cost and ease of operation and cleaning, rather 
than upon any difference in effectiveness. They were used alternately 
on successive days for several weeks, and on three days, September 1 , 
12, and 19, 1910, the milk was divided, one-half being run through 
each. The cheese was first class in each case and showed no differ- 
ences that could be traced to the use of different machines. 

THE ACIDULATION PROCESS. 
THE STANDARD ACIDITY OF MILK FOR CHEESE MAKING. 

Milk as it flows from the pasteurizer varies daily in acidity and is 
lacking in bacteria of the lactic-acid type, needed to aid in cheese 
curing. By the atldition of sufficient hydrochloric acid to raise the 
acidity of the milk to 0.25 per cent (as lactic acid) after pasteurizing, 
and of three-fourths })er cent of a first-class starter, the pasteurized 
milk is brought daily into standard condition both as to acidity and 
bacterial content for cheese-making purposes. The reasons for 
adding acid and starter as specified will now be given in detail. 

The standard acidity is 0.25 per cent, and the acidity of pasteur- 
ized milk is raised to this figure rather than to 0.20 or 0.30 per cent 
for the following reasons: 

First. In regular cheese making the acidity of whey when drawn 
is, on the average, about 0.17 per cent, corresponding to an acidity 



STANDARD ACIDITY OF MILK. 29 

of milk of about 0.25 per cent. Anyone can test the correctness of 
tliis statement by transferring a pint of milk from a cheese vat, just 
before adding rennet, to a small tin pail, keeping the milk sample at 
the same temj^erature as the vat and titrating the milk in the pail as 
well as wliey from the vat at intervals. When the whey reaches 0.17 
per cent the milk reaches nearly 0.25 per cent. 

The control of acidity at the instant the whey is drawn is connnonly 
regarded as most important in regular cheese making. "With milk 
pasteurized at 160° there is little or no increase of acidity (usually 
a])out 0.01 per cent) in whey, before the whey is drawn. The acidity 
of milk is adjusted to 0.25 per cent in this process after pasteurizing 
in order to })arallel ordinary working conditions at the time of drawniig 
the whey. 

Second. IMixed milk in the factor}^ cheese vat is commonly at 0.16 
to 0.18 per cent acidity when received, although often at 0.19 to 0.21 
per cent. It should never be over 0.23 per cent acidity. It is found 
that an addition of hydrochloric acid equal to at least 0.02 per cent 
of lactic acid is required to restore the coagulabihty with rennet to 
such milk after ])asteurization, but the daily addition of only 0.02 
per cent of acid would leave the jnilk of varying acidity, which is 
objectionable. If 0.20 per cent were adopted as the standard acidity, 
after adding 0.02 per cent in the form of hydrocldoric acid, this rule 
would exclude from use all milk having a higher acidity than 0.18 
per cent when received, whicli it is not desirable to do. Only rarely 
is a vat full of milk at 0.23 per cent acidity received at any factory, 
but even such milk can be handled in the routine manner at the stand- 
ard acidity of 0.25 ])er cent by adding the required 0.02 per cent of 
hydrochloric acid after pasteurization. 

It might be stated as a matter of record, not as a precedent for 
factory practice, that vats of milk of 0.24 to 0.28 per cent acidity 
when received have been successfully made up into good cheese with- 
out varying the process in any particular, excepting that only enough 
acid is added after pasteurization to raise the acidity 0.01 per cent, 
which is sufficient to restore the rennet coagulation to such ripe jnilk. 
The only apparent limit of acidity for milk to be handled by this 
process is that the milk should not, of course, be sour enough to 
curdle in the pasteurizer, and this limit is reached at or about 0.30 
per cent. 

However, it should be recognized by everyone that milk that has 
reached 0.30 per cent or even 0.25 per cent acidity before it gets to 
the cheese factory must have received very poor care and attention 
on the farm and must be entirely unfit for cheese making from a sani- 
tary point of view. 



30 CHEDDAR CHEESE FEOM PASTEUEIZED MILK. 

COMPARISON OF DIFFERENT KINDS OF ACIDS FOR USE IN CHEESE 

MAKING. 

Of the more common acids — sulphuric, hydrochloric, and phos- 
phoric — the first is the least convenient to handle, especially in a 
cheese factory, because of the great amount of heat liberated when it 
is diluted, and the impossibility of diluting it in the carboy in which 
it is received. Hydrochloric acid is much better in this respect 
as it can be readily diluted with an equal volume of water by pouring 
the water into the acid with no danger and very little heat evolution. 
Thus diluted it fumes very little, if at all, and can be readily and accu- 
rately standardized by titration with normal caustic soda and phenol- 
phthalein indicator. Phosphoric acid can be purchased in carboys 
of about 50 per cent strength, requires no dilution in the carboy, and 
liberates little or no heat when diluted. 

The choice between hydrochloric acid and acid marie from phos- 
phorus is greatly in favor of the former because of the high cost of 
the latter. Recently, however, phosphoric acid made from bone ash 
or bone black has been put on the market in this country, containing 
about 45 per cent free phosphoric acid and less t^han 1 per cent each 
of hydrochloric acid, sulphuric acid, and phosphates of iron and 
alumina, this product being offered at 6 cents a pound in paraffined 
barrels. The price of this acid is very nearly the same as that of chem- 
ically pure hydrocliloric acid for equal neutrahzing power. 

Chemically pure hydrochloric acid is and has been for years a stand- 
ard article of manufacture, whose purity is tested daily by use in 
hundreds of laboratories. On the other hand, the manufacture of 
phosphoric acid from bone ash in a form free from objectionable 
impurities has been accomplished only very recently. 

A number of cheeses were made with phosphoric acid, but these 
showed no advantage over those made with hydrochloric acid ; indeed 
they seemed to have a slight peculiarity of flavor, as a rule, after curing. 
Most of the cheeses made from pasteurized milk have so far been made 
with hydrochloric acid, and the use of this acid is described and recom- 
mended in the present bulletin. 

The selection of hj^drochloric acid was made because it is cheap 
and more easily obtained than any other chemically pure acid, and 
being a natural constituent of gastric juice in the human stomach, no 
objection could be raised on sanitary or other grounds against its use 
in this process. 

THE PROPORTION OF HYDROCHLORIC ACID REQUIRED DAILY. 

It is necessary to determine first what the acidity of each vat of 
the mixed milk is, in order after pasteurizing to add the requisite 
quantity of hydrochloric acid to bring the acidity up to 0.25 per cent. 
Where only one vat of milk is to be pasteurized and only one workman 



TESTING MILK FOR ACIDITY. 31 

is employed it is probably better to weif!:h in all the milk then stir the 
vat well and take out a half cupful of milk for the acid test. 

Where two men are employed and it is desired to start the 
pasteurizer running as early as possible (before the receiving vat is 
full), the intake man should take from each weig^h can of milk a 
sampling tube full, mixinf; these samples in a pint jar. The acidity of 
this mixed sample will then be the same as the average acidity of all 
the milk run into the vat. As soon as one vat full of milk (say 5,000 
pounds) has been run from the weigh can into the receiving vat, tlie 
pint jar containing the sample for the aciti test is handed from the 
intake to the man running the pasteurizer, together with the total 
weight of milk run into that vat. The pasteurizer was started when 
periiaps only half of tliis milk had been received, but the receiving 
vat is still about half full, and after making the acid test on the sample 
the operator can tell exactly how much more hydrochloric acid must 
be afhled, while pasteurizing the remaining milk in order to bring the 
acidity of the whole vat up to the right point, or 0.25 per cent. 

TESTING MILK FOR ACIDITY. 

In determining the acidity of milk, measure a 17.6 cubic centimeter 
pipette full of milk sample into a white cliina cup, whicii should be 
shallow and wide rather than narrow and deep. Add two drops of 
phenolphthalein inchcator and while shaking or stirring the milk in 
the cup run in tenth-normal alkali (Manns's solution) from a burette, 
rapidly at first, and later by single drops, until the faint pink color pro- 
duced by the last drop does not disappear on thorough mixing. The 
volume of tenth-normal alkali used is read from the burette, and this 
volume divided by 20, which can be done mentally, gives the exact 
acidity of the milk in per cent of lactic acid by weight. For example, 
if the volume of alkali solution used was 3.2 cubic centimeters the 
acidity is 3.2 divided by 20, which equals 0.16 per cent. Subtracting 
the acidity of the raw milk from 0.25 per cent shows how nmch the 
acidity of the milk is to be raised with hydrochloric acid after ]ias- 
teurizing. For example subtracting 0.16 per cent from 0.25 per cent 
leaves 0.09 per cent, which shows that the acidity is to be increased 
0.09 per cent with hydrochloric acid. 

The outfit needed for testing milk is shown in Plate I. It consists of: 

1. A burette with rubber tip and pinchcock; capacity 25 c. c, with 
Yo c. c. graduations. 

2. A 17.6 c. c. pij)ette as used for the Babcock test. 

3. A white chhia teacup, which is best if shallow and wade and with 
flat bottom. 

4. A support for the burette, which may be an iron stand and clamp, 
or a wooden strip with a hole in it, fastened to a window casing, as 
shown at the left in Plate I. 



32 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

5. A nibber-stoppered bottle of Manns's solution (tenth-normal 
alkali) which may be purchased at $1 per gallon of dealers in dairy 
supplies, or may be made by diluting the normal alkali solution, 
which must be purchased as it is required in this process a,s described 
on page 36. 

6. A 2-ounce or 4-ounce bottle of phenolphthalein indicator solu- 
tion. 

7. The additional outfit required for use in this process of cheese- 
making is also shown in the figure. It consists of 1 gallon of normal 
alkali (ten times as strong as Manns's neutralizer), a 50 cubic centir 
meter measuring flask, a 500 cubic centimeter measurmg cylinder, and 
a 2 cubic centimeter pipette, which should be accurately made. A 
gallon of normal caustic alkali contains about 5 ounces of caustic 
soda, worth about 15 cents, and should cost the cheese maker no more 
than a gallon of tenth-normal solution — that is, about SI. 

PRESERVING THE TENTH-NORMAL SOLUTION. 

Instead of using the large bottle of tenth-normal solution to fill the 
burette wdth, it is much better to get a smaller bottle, holding 6 or 
8 ounces, also provided with a rubber stopper, and to fill this 
smaller bottle occasionally from the larger bottle, which is then put 
away, tightly stoppered, in a safe place. The small bottle is kept 
near the burette and used (lady in filling it, and the large bottle is 
thus protected from unnecessary exposure, loss of strength, and from 
danger of spiUing. The use of two bottles in this manner has proven 
most satisfactory in this laboratory and dairy school during the past 
four years. It is recommended ^ as a means of avoiding loss of 
strength through exposure to the air, which has heretofore been the 
greatest difficulty to overcome in the use of Manns's test in the cheese 
factory. 

DILUTING NORMAL ALKALI TO TENTH-NORMAL. 

One may prepare tenth-normal alkali by diluting the normal alkali 
as follows: Pour into a 500 cubic centimeter graduated cylinder 
exactly 50 cubic centimeters of the normal solution measured in the 
50 cubic centimeter flask. Add at once 450 cubic centimeters of pure 
water, either rain water or condensed steam. Pour the mixture into 
a clean glass bottle, mix by shaking, and keep stoppered with a 
rubber stopper to avoid loss of strength by exposure to air. If the 
mixture is muddy or turbid, the water used in diluting was not pure. 
A slight turbidity may be neglected. 

1 Sammis, J. L. The preservation of Mann's alkaline solution in cheese factories. Hoard's Dairyman, 
vol. 40, No. 41, p. 1200. Fort Atkinson, Wis., Nov. 12, 1909. 



165, Bureau of Ammal Industry, U. S. Dept. of Agriculture. 



Plate I. 




05 



<o 



b o 
Q < 



But. 165, Bureau of ANrMAL Industry, U. S. Dept. of Agriculture. 



Plate II 




3uL. 165, Bureau OF Ammal Industry, U. S. Dept. of Agriculture. 



Plate III. 




ADDITION OF ACID TO MILK. 33 

ADDING ACID TO MILK AFTER PASTEURIZATION. 

For this purpose the acid of normal strength is phiced in an acid- 
proof container on a shelf near the outlet of the cooler. A glass bottle 
or a paraffined wooden cask can be used, as shown in Plate III. The 
container has a small opening on one side near the l)ottom, through 
which the acid is drawn by a rubber tube of one-eighth or one-quarter 
inch hi tern al diameter closed by a screw j^inchcock. On the outside 
wall of the container, beginning at the top, a scale is engraved or 
otherwise permanently attached, with graihiations showing pounds, 
halves, and r[uarters of acid delivered. If the container is opaque, a 
glass level-tube placed outsitle near the scale shows the acid level 
withui at any time. The capacity of the acid container shoidd be 
about 10 gallons for use with a 7,000-pound vat of milk. In ad(!iti( n, 
a two-quart tin pan is connected by means of a short piece of con- 
ductor to the cooler outlet. The milk from the cooler and acid from 
the container are thoroughly mixed in the conductor and mixhig 
pan, from which the acididated milk overflows and runs into the 
cheese vat. 

In order to avoid coagulation of milk with acid, the acid is added 
from a jet so as to strike the cooled milk while the latter in a thin 
stream is moving rapidly down the sliort, stee{)ly inclined ])iece of 
open-conductor pipe. The mixture then enters the mixing j^aii and 
its direction is abruptly changed twice, thus securing thorough 
mixing of milk and acid before it flows over the edge of the pan into 
the cheese vat. 

In using tliis acidulator there is never any danger of coagulation if 
the operator remembers always to shut off the acid before the milk 
flow stops. It has been repeatedly shown that 2 pounds of acid, 
or twice as much as commonly required, can be safely added in this 
manner to 100 pounds of milk at 60° to 80° F. without causmg coagula- 
tion. If any small particles of curd are formed, they rise to the 
surface of the milk when quiet hi the vat and can be plainly seen. 
They can then be taken up with a hair sieve and rubbed through the 
sieve into the milk without causing loss of jdeld. In practice, the 
acidity of the vat of milk, when all in and stirred, always comes 
between 0.24 and 0.26 when attempting to make it 0.25 per cent, 
and this degree of accuracy is entirely satisfactory. 

CALCLTLATING THE AMOLTNT OF ACID TO BE ADDED. 

To calculate how many pounds of normal hydrochloric acid are 
required by any vat of milk after pasteurizing, it should be remem- 
bered that 1 pound of the acid added to 100 pounds of mUk will raise 
its acidity just nine hundredths (0.09) per cent. From this it is easy 
79994°— Bull. 165—13 3 



34 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



to see that for 2,500 pounds of milk, of 0.16 percent acidity, just 25 
pounds of normal strength acid will be required, and for 3,050 pounds 
of milk 30.5 pounds of acid will be needed, etc. If the milk showed 
an acidity of 0.21 per cent when raw, then subtract 0.21 from 0.25, 
which leaves 0.04 per cent. In this case, since the milk is riper to 
start with, less acid will need to be added; only four-ninths of a pound 
of acid for each 100 pounds of milk will be necessary to bring the acid- 
ity up from 0.21 to 0.25 per cent. In any case the weight in pounds 



of acid required is equal to 



0.25 — acidity of raw milk weight of milk, 



or 0.25 — acidity of raw milk X 



.09 
weight of milk 
9^0 



^" 100 

Stated hi words the 



rule is, divide the weight of milk by 9 and multiply by 0.25 minus 
the acidity of the raw milk. 

The followuig table shows the amount, in pounds, of normal acid 
required to be added for each 100 pounds of milk when the acidity 
of the latter before pasteurizing is 0.15, and for each one-hundredth 
increase up to 0.27: 

Table 14. — Weight of normal acid required to be added for each 100 pounds of milk. 





Weight of 




Acidity of 


normal 


Aciditv of 


milk when 


acid added 


milk after 


pasteur- 


to 100 


the addi- 


ized. 


pounds of 
milk. 


tion of acid. 


Per cent. 


Pounds. 


Per cent. 


0.15 


1.11 


0.25 


.16 


1.00 


.25 


.17 


.88 


.25 


.18 


.77 


.25 


.19 


.66 


.25 


.20 


.55 


.25 


.21 


.44 


.25 


.22 


.33 


.25 


.23 


.22 


.25 


.24 


.11 


.25 


.25 


.11 


.26 


.26 


.11 


.27 


.27 


.11 


.28 



Where milk appears to be of, say, 0.175 per cent acidity when 
received, it is treated as if it were at 0.17 per cent, dropping the 0.005 
out of the calculation. 

The following table, conveniently posted, may aid in calculating 
the weight of acid required for any weight of milk at any acidity; 



PREPARATION OF NOIIMAL il VDHOC II LOlUC ACID, 



85 



Table 15. — Wcujhl of normal hydrochloric acid required for stated quantities of milk at 

stated acidities. 









Hydrochloric acid 


required when acidity is- 


_ 






Weight 
of milk. 
















































0.27 to 
0.24. 


0.23. 


0.22. 


0.21. 


0.20. 


0.19. 


O.IS. 


0.17. 


0.16. 


0.15. 


0.14. 


Lhs. 


Lbs. 


Lb.'i. 


Lbs. 


Lb.s. 


i6s. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


10,000 


11.1 


22. 2 


33.3 


44.4 


55.5 


66. 6 


77.7 


88. 8 


100.0 


111.1 


122. 


9, 000 


10.0 


20^0 


30.0 


40.0 


50.0 


60.0 


70.0 


so.o 


90.0 


100.0 


110.0 


S, 0(K) 


S.9 


17.8 


26. 7 


35.0 


44.4 


53.3 


62. 2 


71.1 


80.0 


SS. 9 


97. S 


7, 000 


7.8 


15. 5 


23.3 


31.1 


38.9 


46.7 


54.4 


62.2 


70.0 


77.8 


85.0 


6,000 


0.7 


13.3 


20.0 


26.7 


33.3 


40.0 


46.7 


53.3 


60. 


66. 7 


73.3 


T), 000 


5.6 


11.1 


16. 7 


22.2 


27. 8 


33.3 


38.9 


44.4 


50.0 


55.5 


61.1 


4,000 


4.4 


8.9 


13.3 


17.8 


22.2 


26. 7 


31.1 


35.5 


40.0 


44.4 


48.9 


3,(K)0 


3.3 


6.7 


10.0 


13.3 


16.7 


20. 


23. 3 


20.6 


30.0 


33.3 


36. 7 


2,0()0 


2. 2 


4.4 


6.7 


8.9 


11.0 


13.3 


15. 6 


17.8 


20.0 


22.2 


24.4 


1,000 


i!i 


2. 2 


3.3 


4.4 


5.5 


6.7 


7.8 


8.9 


10.0 


11.1 


12.2 


',)00 


1.0 


2.0 


3.0 


4.0 


5.0 


6.0 


7.0 


8.0 


9.0 


10.0 


11.0 


SOO 


.9 


l.S 


2.7 


3. (i 


4.4 


5.3 


6.2 


7.1 


8.0 


8.9 


9.8 


700 


.S 


1.6 


2.3 


3.1 


3.9 


4.7 


5.4 


6.2 


7.0 


7.8 


8. 6 


(iOO 


.7 


1.3 


2.0 


2.7 


3.3 


4.0 


4.7 


5. 3 


6.0 


6.7 


7.3 


."iOO 


.6 


1.1 


1.7 


2. 2 


2.8 


3.3 


3. 


4.4 


5.0 


5.6 


6,1 


■400 


.5 


.9 


1.3 


1^8 


2. 2 


2. 7 


3.1 


3.6 


4.0 


4.4 


4.9 


:f()o 


.4 


.7 


1.0 


1.3 


1.7 


2.0 


2.3 


2.7 


3.0 


3. 3 


3.7 


L'OO 


. 2 


.4 


. 7 


.9 


1.1 


1.3 


1.6 


l.S 


2.0 


2. 2 


2.4 


100 


.1 


. 2 


.3 


.4 


.6 


. 7 


. 8 


.9 


1.0 


LI 


1.2 


7.') 


.OS 


!l7 


. 25 


.34 


.42 


.50 


.60 


.67 


.75 


.83 


.92 


.'iO 


.00 


.11 


.17 


.22 


.28 


.33 


.39 


.44 


. 50 


. 56 


.61 


2.5 


.03 


.06 


.09 


.11 


.14 


.16 


.19 


• -- 


.25 


.28 


.31 



To find how imich normal Lydrochloric ju'id will ])c lUM'dod to 
raise 0,754 ])(ninds, for <'xain])Io, of milk of 0.17 \kv cent acidity to 
0.25 ])or cent acidity, take from the tal)lc the figure given under 0.17, 
o]>])osite (),000, which is 53.3; a(hl to this the figure op])osite 700, 
which is (i.2; then a(hl tlu^ figure o])posite 50, which is 0.44; the total 
gives the number of pounds of acid recpiired, namely, 59.9 pounds. 

PREPARATION OP NORMAL HYDROCHLORIC ACID IN THE CHEESE 

FACTORY. 

Chemically ])ure hych'ocliloric-acid sohitiou, as ])urclias(Ml iii car])oys 
containing a])()ut 120 ])()uiids ea<^ii, contains about 40 ])vr cent l)y 
weight of hydrochloric acid and (iO per cent of water, and costs about 
7 cents a ])oun(L Its stnnigth varies somewhat, and it must be 
diluted with water before it can be achled to milk in this ])ro('ess. 
The preparation of normal-strength acid used in cheesemaking is 
carried on at the cheese factory in tv/o ste})s, as follov,'s: 

First step. — Remove the wooden cap from the top of a fresh carboy 
of acid and loosen the glass ])lug in the neck by tap])ing it on diirerent 
sides very gently with a })iece of wood (not metal) until it can be 
drawn out readily with the hand. Set an empty carboy alongside the 
newly opened carboy. Fill both limbs of a glass siphon with water, 
removing all air bubbles, and insert the two limbs into the carboys at 
once, as shown in Plate IV. When the siphon is in place, as shown in 
the lower figure, the acid will flow from the full carboy into the other 
until in about half an hour each is practically half fuU. Now fill up 



36 CHEDDAR CHEESE FEOM PASTEURIZED MILK. 

each carboy nearly to the neck with water, leaving space enough 
beneath the neck to permit mixing the contents readily by shakmg. 
Tip each carboy up on one edge and rock vigorously for about five 
minutes with the stopper out to induce thorough mixing. The liquid 
gets slightly warmer on mixing, and it is stoppered and left to stand 
overnight to cool and is then called "dilute" acid. 

To determine how much further each carboy of dilute acid requires 
to be diluted with water to make it exactly "normal" in strength, set 
up the burette used in ]\Ianns's test, but fill it with normal alkali solu- 
tion, which is 10 times as strong as that used in testing milk. Using 
a 2 cubic centimeter pipette, transfer exactly 2 cubic centimeters of 
the dilute acid from the carboy to the porcelain cup containing a little 
pure water, letting the pipette drain into the cup half a minute by the 
watch and blowing out the last drop of acid from the tip into the cup. 
Now add one or two drops of indicator and after reading the level of 
alkali in the burette, draw out the alkali from the burette, precisely as 
in testing milk, rai)idly at first, later by single drops while shaking 
the cup in a circle until the last (h'op added produces a distinctly pink 
color which remains throughout the entire liquid after thorough mix- 
ing. Read and record the volume of alkali solution used. Rinse out 
the cup, fill up the burette, shake up the acid in the carboy for a 
minute and test another 2 cubic centimeters of the acid for the sake 
of accuracy. 

If the contents of the carboy were thorouglily mixed at first, the 
two titrations will agree closely, not diil'ering by more than 0.20 cubic 
centimeter. If they do not agree, the carboy contents were probably 
not weU mixed at first, and should be given another very thorough 
shaking for five minutes, after which the titrations are repeated. 
Once thoroughly mixed the acid and water remain mixed, and never 
need to be shaken again. 

Suppose that in the two tests the 2 cubic centimeters of acid 
rec|uired 11 and 11.2 cubic centimeters of normal alkali to produce 
the pmk color, the average being 11.1 cubic centimeters. Divide the 
volume of alkali by 2 — the volume of acid used — which gives in this 

case ^' =- 5.55. This means that the acid is 5.55 times as stron<r 

2 * 

as it should be for normal acid, and that it must be diluted to 5.55 
times its volume with water to make it exactly normal in strength. 

The work described above is performed once on each carboy of 
dilute acid before using it for cheesemaking, and the object is to get 
the figure (5.55 in this case) which shows how much too strong the 
acid is, and how much it must be diluted to make it normal in 
strength. 

Second step. — -The second step consists in diluting up, each day, as 
much of the acid as will be needed for the milk on that day. This 



BuL. 155, Bureau of Animal Industry, U. S. Dept. of Agriculture. 



Plate IV. 





FULL CARBOY OF 
HYDROCHLORIC ACID 



EnPTY CARBOY 



Transferring Acid from Full to Empty Carboy by Means of Siphon. 



iuL. 165, Bureau of Animal Industry, U. S. Dept. of Agriculture. 



Plate V. 




DIRECTIONS FOR PASTEURIZING AND ACIDULATING MILK. 37 

is ])orformed as follows: Having determined that the dilute acid is 
5.55 times stronger than normal, the acid is further diluted for use 
each day, adding 1 volume of acid to 4.55 volumes of water, thus 
making the total volume 5.55 times as great as the acid used. 

To do this, measure out any convenient volume (say 500 cubic 
centimeters for about 2,500 pounds of milk) of the acid m a glass 
cylinder and add it to 4.55 times its volume of water (m this case 
500x4.55 = 2,275 cubic centimeters water). The acid should always 
be measured, but if more convenient the water can be weighed in 
pounds if it is remembered that 453 cubic centimeters of water weigh 

2 275 

1 pouiKJ. In this case ' =5.02 ])Ounds of water needed. 

The acid and water can be mixed in the acidulator or in a wooden 
pail, or in a bright tm ])ail, if the water is ])ut in first and the acid 
added later. After the proper amounts of acid and water have been 
poured into the acidulator, they should be thoroughly mixed at once 
by stirring with a wooden ])addle, and once thoroughly mixed the 
normal acid is always ready for use. Of course the acid should not 
be handled in galvanized iron or aluminum vessels, as it will rust 
them. The undiluted acid will also discolor tinware and should be 
measured ui the glass cylinder, as dii'ected. The "dilut(>" acid is 
drawn from the carboy into a gallon glass bottle through a glass 
sij)hon, which is fh'st filled with water. The water used in tlu^ siphon 
is so small in volume^ — about 1 per c(>nt of a gallon — that it does not 
noticeably affect the strength of the acid. 

There is nothing dilKcult about the preparation of normal-strength 
hydrochloric acid for use in cheese making, and anyone who knows 
how to titrate milk for acidity can learn to do this also. To test the cor- 
rectness of the work when completed, transf(>r two cubic centimeters 
of the acitl with a pipette from the acidulator to the porcelam cuj), 
and titrate it with, the normal alkali ui the burette. The volume of 
alkali required should be between 1.9 cubic centimeters and 2.1 cubic 
centimeters, or, better, exactly equal to the volume of acid used. 

The degree of accuracy required in this whole process is very easily 
attained, as quite satisfactoiy results will be obtained in acidulating 
milk if the normal acid used is anywhere between 0.95 and 1.05 normal. 

GENERAL DIRECTIONS FOR PASTEURIZING AND ACIDULATING 

MILK. 

The method described is well adajited for use in a large factory. 
At a factory handling two to three large vats of milk daily two men 
should be employed. The inspection and weighing of milk at the 
intake is performed by one man while the other makes the determi- 
tions of acidity and runs the })asteurizer. After the milk is all in 
and })asteurized the two men work together, heating ui) the vats, 



38 CHEDDAR CHEESE FROM PASTEURIZED MlLK. 

adding the starter, color, and rennet to the vats at least 10 or 15 min- 
utes apart. They cut the curds in the same order, each 25 minutes 
after the rennet has been added, and start the agitators in each curd 
as soon as cut. The vats are heated up and the whey is drawn from 
the vats in the same order, both men working- together in putting 
the curds on the rack, fhiishing each vat of curd m time to handle 
the next. 

If more than three vats are handled in one factory, additional help 
will be needed, especially for bandaging hoops, turning cheese, and 
other labor. 

\\^iere only one vat of milk is handled daily, the milk is run first 
into the receiving vat, from which it flows into the pasteurizer, 
through the coolei', and into the cheese vat. If two vats of milk are 
handled daily, the first milk received may be run mto one cheese vat, 
from which it is pasteurized into the other cheese vat, while the milk 
received later is run into the steel receiving vat, from which it is 
pasteurized into the second cheese vat. 

If throe or more vats of milk are handled daily, the receiving vat 
and the first cheese vat are filled alternately with milk from the in- 
take, and alternately emptied through the jxisteurizer into the other 
cheese vats. It is only necessary to see to it that the last vat filled 
from the intake shall be the receiving vat in order that this last milk 
may be run into one of the cheese vats after pasteurization. One re- 
ceiving vat is needed in addition to the necessary cheese vats wherever 
this ])rocess is used. 

MAKING READY TO PASTEURIZE. 

Since pasteurization is essentially a cleaning process, care should 
be taken to keep the make room, the vats, machinery, etc., and every- 
thing with which the pasteurized milk comes in contact as clean as 
possible. 

Although milk flows intermittently from the weigh cans, it is de- 
sirable that the pasteurizer, once started, shall run continuously, with 
a steady milk sui)])ly, and for this purpose a receiving vat is pro- 
vided. The milk should be run into the receiving vat through a 
strainer which will remove all flies, straw, etc., and which can not 
by accident fail to work ])ropcrly. Such a strainer is shown m Plate 
V. It is set up by slipping a piece of seamless cheese bandage over 
the wooden frame of the vat strainer and placing the metal part on 
top. The metal part collects all large pieces of dirt and prevents the 
milk from splashing over the side. The two thicknesses of cheese- 
cloth effectually remove finer particles of dkt. This arrangement 
has been used in this series of experiments for about two years and is 
heartily recommended. Of course the cloth should be scalded daily. 



OPERATION OF THE PASTEURIZER. 39 

The weigh can, conductors, receivmg vat, and pasteurizer should 
be washed daily, immediately after use, and again linsed with clear 
hot water before use, if necessary. The pasteurizer and cooler and the 
connecting pipes should be washed thoroughly daily. Just before 
starting the pasteurizer each morning the operator should rinse out 
the cheese vat and steam it by running steam into the jacket. The 
])asteurizer and delivery pipes, especially those parts which are hi 
contact with the cooled pasteurized milk, should be also scalded or 
steamed. This can be done by running a couple of pails of hot water 
into the heathig compartment, heating it there to 180° or higher, 
and running it over the cooler without having any cold water inside 
the cooler. 

Where only one vat of milk is being pasteurized, the acidulator may 
be set on the edge of the vat, but to avoid moving it, when several 
vats of milk are handled daily, the acidulator should be set near th(> 
pasteurizer and the acidulated milk run into the different vats 
through a moval)le conckictor, as shown in Plate III. 

STARTING AND STOPPING THE PASTEURIZER. 

Wlien milk enough has been received to insure a continuous supj)ly 
for the pasteurizer, the latter may be started. 

First, see that everything is in place and that the pump supplying 
water for cooUng is running. Set the pasteurizer in motion, turn on 
a little steam, and run enough milk into the heating compartment 
nearly to fill it so as to register its temperature on the naked glass 
bulb of the thermometer placed near the exit to the cooler. Do not 
allow any milk at all to run into the cooler. If any does by accident, 
draw it out and scald the cooler with a pail of hot water. 

Open the steam valve to the full running capacity. Wlien the 
thermometer in the milk registers about 155° start the milk supply 
again and adjust so that the thermometer stands at 162° at the exit 
from the heater. ITse care to see that no milk at all is allowed to nin 
to the cooler at a temperature below 160°. If any irregularity occurs in 
starting, it is much better that the first milk should be heated higher 
than 160°, even up to 180°, rather than that any portion should pass 
over into the cheese vat without reaching 1 60°. It will do no harm at 
all if for a few minutes at first milk at 170° or 180° passes over into the 
cooler, because this milk will at least be thoroughly pasteurized, but if 
milk at 140°, or any temperature below 160°, passes over it may carry 
over harmful bacteria which ma}' injure the entire vat of cheese. A 
file mark on the steam-valve handle is a great help in quickly adjust- 
ing the steam supply to the right point. 

Once adjusted, and with steady milk and steam supply, the pasteur- 
izing temperature remains nearly constant and i-equires only momen- 



40 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

tary iiispecli(>n every few minutes. No doubt an automatic tempera- 
lure-controlling device could be used to advantage here. 

Although the thermometer now supplied with some forms of 
pasteurizers is metal jacketed to prevent breakage, yet in all the 
experiments here reported this metal-cased thermometer was found 
to register more slowly than a naked glass-bulbed thermometer, set in 
a rubber stopper. The latter kind has been in use two years without 
breaking and is therefore preferred. 

In stopping the pasteurizer for any reason, the operator should 
remember to stop the acidulator first, then the milk supply, and last 
of all the steam. If the stoppage is for long, as at the end of tlie 
day's run, the hot milk in the heating compartment is drawn out in a 
pail (its temperature should be 160° or above) and added to the vat. 
The milk in the cooler is also drained and rinsed, if desired, into the 
vat. 

The water supply for cooling must be ample so that a thermometer 
placed in the millc flowing from the cooler is not above 85° at any 
time, and preferably at 80° or lower, since the milk in the vat can 
easily be heated to 85°-86° for setting with rennet, but can not so 
well be set, or easily cooled, if above 86°. 

STARTING AND STOPPING THE ACIDULATOR. 

As soon as the pasteurizer has been started and regulated the 
pinchcock at the acidulator is opened, allowing one or more small 
streams of hydrochloric acid to run into the millc. The height of the 
liquid in the acidulator should be marked on the glass scale with a 
pencil or string, when starting, and another mark placed lower down 
on the scale to show how much acid is to be drawn out for that vat 
of milk. B}'' this means the operator can see from any part of the 
room when the acidulator is ready to be stopped. Always stop the 
acidulator before stopping the milk. 

THE USE OF BACTERIAL STARTER IN THE NEW PROCESS. 

THE REASON FOR ADDING STARTER IN MAKING PASTEURIZED-MILK 

CHEESE. 

The addition of the required amount of hydrochloric acid to milk 
raises its acidity at once to 0.25 per cent, but does not cause any fur- 
ther increase of acidity at any time. Of the acid thus added, only 
about one-fortieth remains in the curd, the rest escaping in the whey. 
No chemical method has been found for increasing the acidity of a curd 
on the rack, so that if acid plays any important part in the cheese- 
curing process, it will be necessary to add bacteria to the milk in order 
to develop the necessary acid in the curd and cheese. A number of 



THE USE OF BACTERIAL STARTER. 



41 



expcrimonls were performed in wliich the milk supply was divided 
and made up in diirerent vats, using diiYerent proportions of starter. 
The cheese was finally scored by Mr. J. W. Moore with the following 
results: 



Table 16. 



-Qiinlifij of cheese made from pasteurized milk with varying amounts of starter 
added. 



Date. 
made. 


Cheese 
No.i 


Propor- 
tion of 
starter. 


Tempera- 
ture of 

jjasteuri- 
zatiou. 


Score. 


Flavor. 


Texture. 


10(W. 
Auu. 17 

IS 

19 

20 
21 

22 

.31 

.>:-o:it 1 


1070c 

1079 

lOSl 

10S3 

10S,5c 

1087 

1SS9 

1091 

1093c 

1095 

1097 

1099 

1101c 

1 103 

1105 

JlO.lc 

im 

1113 

1115 

1117c 

1119 

1121 

1123 

11.57c 

1159 

llfil 

1103 

1 10.5c 

1 107 

11(19 

1170 

1173c 

1175 

1177 

1179 

1024 

l(>2i) 


Per edit. 


T. 


40. .50 
40. 50 
41.25 
42.50 
41.00 
41.75 
41.00 
4t).25 
40.. 50 
41.25 
42.50 
42. 75 
41.25 
42. .50 
42. 25 
40.75 
42. 25 
42. .50 
42. .50 

39. .")l) 
42. 25 
41.75 
42.25 
41.00 
41.00 
42. .50 
42. ,50 
39. 00 

40. ,50 
42.00 
42. .50 
40. 00 
41.00 
41.00 
41.. 50 
Sour. 
Sour. 


27.00 

27^25 
2.S. 00 
27.25 
27.75 
27.25 
27.00 
27. (XI 
27. (H) 
27.75 
2S. m 
27.00 
2s. 25 

h.m 

27.25 
27! 25 

27.00 

27! 00 
27. (K) 
27.00 
2S. 00 
28.00 
2S. .50 
20. 00 
27.. 50 
2,S. (M) 
27. (Kl 
2fi.(K) 
27.00 
27.00 

Color-cut. 

Color-cut. 


0. 25 

. ,50 
.75 


157 
157 
157 


.25 
..50 
.75 


157 
157 
157 


!.50 
.75 


157 
1.57 

157 


.75 


1.57 
1.57 


. 75 
1.00 
1.25 


1.57 
1.57 
1.57 


.75 
1.00 
1.25 


1.57 
1.57 
1.57 


Noii(>. 
.3 
.0 


102 
102 

162 


None. 
.3 
.0 


11)2 
lt>2 
102 


Noiii'. 

.3 

.0 

3.0 

5. 


102 
]il2 
102 







1 "e" in thi^ column imlicates raw-milk cheese. 

These scores may he summarized as follows: 

Tahle 17. — Summary of scores in Tabic 16. 







Average scores. 




Numlier 
of cheese-; 




1 












scored. 


Flavor. 


Te.xture. 


Comtiined, 


Per cent. 













3 


40. S3 


20.33 


(i7. 16 


0. 25 to 0. 30 


7 


41.04 


27.53 


(9,18 


.5 to .0 





41. SS 


27.54 


(;9, 42 







42. 04 


27. .50 


09.. 54 


1.(1 


■) 


42. 12 


27. 25 


09.37 


1.25 


- 


42, .37 


27.37 


(■i9. 75 



42 CHEDDAR CHEESE FEOM PASTEURIZED MILK. 

These scores indicated that the cheese obtained by three-fourths, 
one, or one and a quarter per cent starter are about equally good, 
considering both flavor and texture, and the use of three-fourths per 
cent starter has been continued since August, 1908, to the present 
time, with good results. The starter used should be first class in 
quaUty, just beginning to thicken, containing the maximum number 
of lactic acid bacteria in active condition, and free from all objection- 
able germs or flavors. 

Only a starter above criticism, such as every good cheese maker 
should know how to prepare, can be used with pasteurized milk. If 
the starter is at all tainted it is sure to damage the flavor of the cheese 
to some extent. With raw, badly tainted milk, especiaQy in warm 
weather, a starter of only fair quahty will often greatly improve the 
quaUty of a vat of cheese, but pasteurized milk is freed from practi- 
cally all taints by the pasteurization, and to such milk only the best 
starter can safely be added. 

The importance of a good starter was made apparent when, begin- 
ning June 9, 1910, nine days' make of pasteurized-milk cheese proved 
to be gassy and oft" flavor, and bacteriological examination of the 
starter as well as of the cheese demonstrated the presence of the same 
gas-forming organism in both. It was clear that the organisms in 
question did not pass through the pasteurizer, since their thermal 
death-point was found to be lower than the pasteurization tempera- 
ture (160°) employed in the j^rocess. Therefore there could be no 
doubt that the improper preparation of milk for propagating 
"startoline" was the cause of the trouble in this case. 

A PRACTICAL STERILIZER FOR THE CHEESE FACTORY. 

The essential equipment for propagating a starter is some sort of a 
sterihzer, an incubator, and a sup])ly of a dozen pint cream bottles 
which are best provided with fairly tight tin covers about 2 inches 
deep. Various diflerent sterihzcrs have been recommended, the sim- 
plest being an inverted tin pail covering the bottles of milk on the 
steam table. For use as an incubator, a small covered shotgun can 
may be steamed out daily, and after placing the bottles therein and 
adjusting the cover it may be carried to the ice box, the cellar, a hay 
cooker, or any room of suitable temperature. Wliere bottles of 
starter must be handled and carried about there is always some 
danger of their becoming infected, and this can only be prevented by 
intelligent work on the part of the operator. On account of its small 
size a culture propagated in a bottle is often called a "startoline," 
meaning a Httle starter. A combined sterilizer, cooler, and incubator 
made of galvanized iron has been devised, and used in our work 
during the past year with entire satisfaction. Its use saves time in 



PKEPARATtON OF THE STARTER, 



43 



htindling and reduces the danger of contamination to a mininnini. 
It is shown in figure 1 . 

The apparatus consists of a galvaiiized-iron container with cover, 
a movable false bottom, and with steam, water, and drain connections. 
Where i)int bottles are used, the ])erforated shelf is raised and set on 
lugs as shown. If quart bottles are used, the perforated l)ottom is 
lowered, so that- the to]) of the l)()ttle always stands at the top of the 
sterilizer. 




vjai- fon CAP FOR -^MnrruFS^' -'■'' 

niLK BOTTLE WATER BOTTLE J INUI v.nL^ 4 x a 

Fig. 1. — Combined stcrilizor, cooler, and inciilnitor for eliepse-factory starter. 
PREPARATION OF THE STARTER. 

The bottles having been cleaned and fiUed nearly full with the 
l)est whole milk obtainable are each covered with a tin ca}) and set in 
the sterihzer, together with one bottle of water carrying the ther- 
mometer. The Hd is })ut on and the steam turned on very slowly at 
first, by turning handle a. After the thermometer ])rojec-.ting through 
the small hole in the hd shows that the contents of the bottles are 
heated to 200° or above, the steam is left running for three quarters 
of an hour, and then turned off. To cool the bottles of steriUzed mdk 
o])en valve h and slowly run in cold w^ater, wliich escapes at the 
overflow c. If the water is turned on l)y mistake faster than the 



44 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

overflow can carry it off, the tin caps will keep it from entering the 
bottles of milk. When the thermometer sliows that the bottle con- 
tents are cooled to about 70° the water may be turned nearly or 
entirely off. The bottle of "startoline" from the previous day, 
which has not yet been opened, is now brought in and a portion, 
about a tablespoonful by guess, is poured into each bottle of newly 
sterilized milk in the apparatus, lifting the tin caps for an instant for 
tliis purpose. The room should be free from drafts, floating dust, 
or other source of contamination, and the transfer should be made as 
quickly and carefully as possible. The cap is then replaced and the 
cover put on. The temperature of the water can be kept between 
60° and 70° for a few hours, and in the evening, in summer, if the 
weather is very warm, a piece of ice can be added to -the water. 

This daily process of propagating the "startoline" was performed 
in the cheese factory during the year 1911 by Mr. A. T. Bruhn, with 
entire success, carrying along the same culture of bacteria throughout 
the year. Each day after inocidating the fresh bottles of milk, the 
remainder is examined by pouring out a httle in a teaspoon or cup, 
to be tasted and smelled to see that it is in good condition;' and if so, 
the remainder in the jar is used in making up starter for the next 
day's cheese A'at in the following manner: 

To prepare starter from this "startoline," jdace in a shotgun can 
about eight or nine pounds of milk for each thousand received daily, 
cover up, and heat in a tub or deep pail of water by passing steam 
until the water is boiling and a thermometer in the milk reads at least 
180°. Keep it at this temperature for three-quarters of an hour and 
then cool by filling the tub with cold water, A dash stirrer whose 
handle is slipped through the smallest possible hole cut in the cover 
is a convenience and saves opening the can for stirring. Wlien thor- 
oughly cool — about 70^ — add to the contents of the can the remain- 
ing contents of the "startoline" jar, as stated above. Stir this weU 
and leave for five or six hours at this tem})erature, after which it 
may be put in a cooler place to stand overnight. 

The general principle on which the temperature of starters, 
etc., is regulated is that the starter should ripen only fast enough so 
as to be barely tliick, or- just getting tliick, when required for use 
next day. If the acidity increases too rapidly at first, the bacteria 
are kept too long before use in a liighly acid medium, not favorable 
to their growth, and in general this is to be avoided. The tliickening 
of the milk at about 60° or 70° may be taken as an incUcation that 
the acidity is in the neighborhood of six-tenths per cent, wiiich is 
about as liigh as it ought to go for this purpose. 

To control the temperature for ripening is not so likely to be 
troublesome as to avoid getting dirt and foreign bacteria into the 
"startoline" or starter after it has been once thoroughly sterihzed. 

1 To test further the quality of the starter, a bottle of the thickened milk, unshaken and unopened, may 
be set away in a warm place for a day or two, to see if gas bubbles or unpleasant flavors develop. 



TIME SCHEDULE FOR MAKING CHEESE. 



45 



Strictly spealdng it is impossible to sterilize milk so perfectly as to 
kill all s{)ores hy one such heating, and on this account attention 
should be given to selecting the best ])ossible milk for starter maldng. 

At the beginning of the season a small bottle of bacterial starter 
can be obtained from dealers or from a college of agriculture. 

It is well to begin propagating the starter several days before 
cheese making is to begin, and also to carry along two or more starters 
from different sources, separately, in order that if one is lost or found 
unsuitable another may be at liand. 



METHOD OF MAKING CHEESE BY THE NEW PROCESS. 
GEXERAL ARRANGEMENT OF SCHEDULE. 

In making cheese by the new method the cheese maker is reheved 
of a great deal of the uncertainty wliich attends cheese making by 
the ordinary methods. Having inspected the milk at the intake and 
rejected any tliat is curdled or otherwise unfit for use, he determines 
by means of Manns's acid test the acidity of the entire vatful of 
mixed milk. This may be anywhere from 0.14 to 0.25 per cent, or 
even a little liigher, but if much above 0.28 per cent the milk is hkely 
to curdle and clog tlie pasteurizer. He then runs the milk through 
tlie pasteurizer and adds to the cold milk as it flows into the cheese 
vat enough dilute hydrochloric acid to raise the acichty of the whole 
vat to just 0.25 per cent (calculated as lactic acid). Three-quarters 
per cent of a first-class starter is added, and after heating to 85° the 
color and rennet are stirred in immediately. 

The rest of the ])rocess is conducted according to a fixed time 
schedule, which is never varied. The time from adding rennet to 
hooping the curd is always exactly five liours and fifteen minutes, 
and the intermediate process is as shown in Table IS. This is carried 
on every day in the season without exception. 

Wliile it may be found desirable or convenient at some factories 
to modify somewhat tliis routine, described below, j^^et it appears 
practically certain that whatever routine of operations is adopted 
at any factory, it can be followed without mocUfication throughout 
the season. 

Table 18. — Time schedule for making cheese by the new method. 



Operation. 



Adding rennet 

Cutting the curd 

Beginning to heat 

Turning off steam 

Placing rack after drawing whey 

Milling the curd 

Salting the curd 

Hooping the curd 




46 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

For example, if the rennet were added to the milk at exactly 9 
o'clock the curd would be ready to put in the hoops five hours and fif- 
teen minutes later, i. e., at 2.15 in the afternoon. As soon as the reimet 
is added it is best to have a written schedule showing the time when 
each operation should be performed. Having once learned how to 
perform each operation in tliis method of cheese making it is only 
necessary to do everytliing in as uniform manner as possible in order 
to get satisfactory results daily throughout the season. There is 
never any need to hurry the process if the milk was overripe at the 
beginning, because the lactic-acid bacteria are practically all killed 
by the pasteurization. The same is also true of the gas-forming 
bacteria, so there is no time lost in worldng gas out of the curd. 
There is no reason for waiting to ripen the milk at the beguming of 
the process before adding rennet. 

UNIFORM PROPORTION OF COLOR USED IN 1911, AND RENNET REQUIRED. 

Color. — Tliroughout the season of 1911 two-thirds of an ounce of a 
standard make of cheese color per thousand pouncls of milk was used, 
giving the clieese a mecUum shade of color. These cheeses were 
sliipped into a number of different cities and appeared satisfactory 
to dealers in all parts of the country, except in Philadelphia, Pa., 
and Boston, Mass., where some dealers asked for white and others 
for liighly colored cheese, as is shown by the following extracts from 
letters. Where more tlian one extract appears from the same city 
they are from chfferent dealers. 

Boston, Mass Our market uses white cheese exrhisively. 

Boston, Mass Use both white and colored. 

Boston, Mass A very light color would not du for this market. 

Chicago, 111 No comment on color. 

Fond du Lac, Wis A little too light color. 

Geneva, N. Y No comment on color. 

Marshfield, AVis No comment on color. 

Minneapolis, Minn No comment on color. 

New York, N. Y Color is exactly right. 

New York, N. Y Should be a trifle higher color. 

Philadelphia, Pa Have to have white cheese for Philadelphia. 

Plymouth, Wis No comment on color. 

Sheboygan, A\'is A good commercial color, but might stand a trifle more color. 

Sheboygan, Wis No comment on color. 

St. Louis, Mo No comment on color. 

Washington, D. C Most of our customers want it colored. 

Waterloo, Wis No comment on color. 

Rennet. — The same proportion of rennet is always used in this 
process, because the milk is alwa3^s in the same condition as to acidity 
at the time of adding rennet, and always ripens equally fast afterwards. 
Therefore, ha^^ng once selected the most suitable proportion of 
remiet, there is no reason for changing it. The use of 2 ounces of 



ADDING STARTEK, COLOR, AND RENNET. 47 

Hanson's or Marschall's rennet per thousand pounds of milk is adopted 
as the best practice, since this quantity produces visible coagulation 
in 7 minutes, as shown in Table 2, and the curd is in prime condition 
for cutting in 25 minutes after adchng rennet. If the rennet extract 
is weaker than it sliould be, such amounts should be used as will 
cause coagulation in the time stated. 

If a larger proportion of rennet than 2 ounces per thousand 
pounds were used, there would hardly be tijne for tlie milk to become 
quiet before visible thickening began, and the curd might be damaged 
and broken through thickening while still in motion. On the other 
hand, over two years' experience with the method has sliown that 
there is no need for using a smaller proportion of rennet than 2 
ounces. Good cheese can be made with 1 ounce of rennet per 
thousand pounds of niilk, but the coagulation of the niilk is unnec- 
essarily slow. 

As in regular cheese making, great care must be taken not to 
measure or dilute renn(^t extract in an}- container in whicli there is 
present the least trace of cheese color, because the cheese color is 
strongly alkaline, and rennet loses its coagulating power almost 
instantly when in contact with alkalies. 

ADDING STARTER, COLOR, AND RENNET TO THE MILK. 

The temperature of all the mixed milk after pasteurizing is never 
above 85° and commonly only 70° to 80°. The acidity may be 
tested, if (k^sired, and should be just 0.25 per cent, or between 0.24 
and 0.26 per cent. Three-quarters of a pound of starter per hun- 
dredweight of jnilk in the vat is added immediately through a liair 
sieve, stirring the milk. The rake is then put in and the vat stirred, 
while heating up to 85°. The desu'ed amount of color is stirred in, 
and always, without exception, the rennet is stirred in last of all. 
The rennet extract measured out for 5,000 pounds of milk should be 
diluted in a pailful of water. In adding rennet, hrst stir the milk 
across the vat the short way, going rapidly from one end of the vat to 
the other. With the largest-sized vats, two men with rakes may 
begin at the middle and walk toward the ends while stirring. Then 
walk back along the vat, adding the diluted rennet from a pail to the 
milk which is still in vigorous motion, noting on the clock the instant 
when the rennet first enters the milk. Set down the pail and again 
stir the milk across the vat the short way, with the rake or rakes, for 
exactly one minute, in which time the operator should be able to 
walk up and down the vat three or four times. In this way the 
smallest as well as the largest vats of milk should be set. Take out 
the rakes promptly one minute after the rennet entered. Cover the 
vat at once, and leave undisturbed. No top stirring is necessary or 
permissible, as the milk begins to thicken almost exactly seven niin- 



48 CHEDDAR CHEESE FEOM PASTEURIZED MILK. 

utes after adding rennet, before there is any visible cream rising. 
Follow exactly the directions as to temperature, acidity, and propor- 
tion of rennet every day in the season. 

CUTTING, STIRRING, AND HEATING THE CURD. 

The curd formed in this process is always ready to cut exactly 25 
minutes after the rennet entered the milk. Therefore as soon as the 
rennet has been added it is best for the operator to write the entire 
time schedule, as shown in Table 18, for the rest of the day's work 
on a paper, or, better, on a blackboard, which can be seen across the 
room. Some operators may suppose that possibly the curd might 
be cut a little earlier or later, but experience has shown that the curd 
is always in a thoroughly satisfactory condition for cutting just 25 
minutes after adding rennet. There is therefore no need for repeated 
testing of the curd with the finger; it is only necessary to keep an 
eye on the clock, and follow the time schedule. 

In cutting, begin \\4th the horizontal knife and cut lengthwise of 
the vat; then use the vertical knife across the vat, cutting alternately 
toward and away from the operator. Finally cut lengthwise, with 
the vertical knife. Do not cut the vat more than once in each direc- 
tion, and try to do the cutting in exactly the same manner every day. 
The different cuts should not lap, nor should portions of the curd 
wider than three-eighths of an inch be left uncut between the knives, 
except in the following case: In cutting next to the sides of the vat, 
as in the first and last cuts in each direction, hold the knife as close 
to the metal sides of the vat as possible. If the knife does not appear 
wide enougli to cut the remaining ciuxl at the last stroke, cut close to 
the tin and leave a narrow strip of uncut curd, not at the edge of the 
vat, but between the last cut and the next to the last. This strip 
will be cut more thoroughly by the knives moving in other directions 
than if it had been left next the tin. Knives with blades three-eighths 
of an inch apart are required for this method. 

Immediately after cutting put the agitator blades in place and 
start them in motion. The curd obtained in this process is so firm 
and solid that this can always be done safely. Go around the vat 
with the hand some time during the next 15 minutes, loosening the 
curd from the sides, bottom, and corners of the vat. A form of agi- 
tator which is very satisfactory has one pair of revolving blades 
which also move up and down the vat, somewhat resembling the 
motion of the rake. 

Exactly 15 minutes after cutting turn steam into the jacket of the 
vat, and raise the temperature gradually during the next 20 minutes — 
just 19° to 104° — which temperature is maintained until the whey 
is drawn. 



BuL. 165, BuHEAu OF Animal Industry. U. S. Dept. of Agriculture. 



Plate VI 




MISCELLANEOUS OPERATIONS IN CHEESE MAKING. 49 

DRAWING THE WHEY, MATTING, CUTTING, AND TURNING THE CURD. 

The agitator is left running until about two minutes before the whey 
is to be drawn, when it is removed, and the curd, after settling a few sec- 
onds, is ]nished slowly away from the gate with one or two rakes. The 
whey strainer is placed inside the vat and the hair sieve below the gate 
in the conductor, the gate being opened at such a time as will permit 
the whey to be out and the first rack to be put in ])lace at the time 
given in the schedule. When the whey is nearly all out, the gate end 
of the vat is lowered gradually, and a few seconds later the curd is 
pushed down toward the gate, leaving the upper third or half of the 
vat bottom bare and free from whey. In this process the curd is 
always sufficiently firmed in the whey so as not to need any stirring 
in the whey or on the rack. With r(>asonably brisk work the curd 
can be transferred to the curd cloth on the rack with a curd pail or 
scoop before it has time to become lumpy on the bottom of the vat. 
Each pail of curd as it strikes the rack shouUl fall apart loosely and 
not show the pi'csence of great lumps of curd matted together. Any 
such lumps should be lightly broken u]) with the hand, and if many 
lumps ap})ear it indicates lack of skill and quickness. 

The curd is piled evenly on the rack about 4 or 5 inches thick, 
and the top is leveled oiT with the hand in the usual manner and cov- 
ered with a curd cloth. More racks if necessary are put in place and 
the vat is fuially covered, leaving the curd to drain. The little curd 
gauge, made of wood, devised during the course of these experiments 
is a help in getting the layer of curd of the right thiclcness and also 
gives a good square end to the curd, which makes it easier to cut into 
blocks of uniform shape. (See PI. VL) 

Just 15 minutes after the time scheduled for putting in the rack 
the curd gauge is removed and the cutting of the matted curd into 
blocks 8 inches square, or G by 12 inches, is begun. 

The blocks are turned over immediately after cutting, and again 
turned 15 minutes later. They are then turned once in 10 minutes, 
and one hour after drawing tlie whey are jiiled two deep, and replied 
every 10 minutes until milled. In turning and ])iling, care is always 
used to turn the outer cooler surfaces toward the inside, in order that 
the entire mass of curd may remain at ])racticall3" uniform temperature 
throughout, as in ordinary ])ractice. 

MILLING, SALTING, AND HOOPING THE CURD. 

Exactly one and a half hours after the whey is drawn the curd is 
milled. The milled curd is piled along the sides of the vat, so as to 
drain toward the middle. It is stirred up with the hands from the 
bottom, turning the ])ile over about once every 10 minutes after 
milling, so as to cool it somewhat, ])revent matting, and allow free 
79994°— Bull. 165—13 i 



50 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

drainage. Little or no white whey ever escapes from the curd after 
mining or salting when made up by this process, although some clear 
whey or brine does drain away. 

One hour after milling salt is thoroughly mixed with the curd at 
the rate of 2 pounds of salt per hundred of curd, which amounts 
practically to 2 pounds per thousand of milk in the spring and early 
summer, and 2\ pounds per thousand of milk in the fall, when the 
yield of cheese per hundredweight of milk is somewhat greater. The 
curd is stirred over several times during the next 20 minutes, by 
which time the salt is all dissolved, and the curd, at a temperature of 
82° to 86°, is ready to be hooped. Each hoopful of curd is covered 
with a cloth and follower as soon as filled, in order to prevent the sur- 
face of the curd from cooling so far that it might fail to close well in 
the press. 

It is of the utmost importance that every cheese should be well 
closed and develop a perfect rind, free from cracks or other openings. 
Where openings occur mold is sure to enter during the curing process, 
and the flavor especially is apt to suffer as a result. 

PRESSING AND DRESSING THE CHEESE. 

Throughout the present set of experiments the cheese has been 
pressed for about an hour, applying pressure with the hand lever 
only, and at first only sufhcient pressure is used to keep the drippinga 
running from the hoops. After an hour the cheese is dressed and 
returned to the press, when continuous pressure is put on and it is 
left for the night. 

In bandaging the hoops the usual starched circles are used under 
the heavy muslin or duck cap cloths, or if it is found that the circles 
are hard to remove for paraffining they may be left out and the cap 
cloths left on the cheese until paraffined. The cap cloths, being of 
heavy cloth, can be stripped off rapidly without tearing and washed; 
m this way they may be used many times. The next morning it is 
customary, as in cheese factories generally, to look over the cheese, 
straighten any bandages which may be faulty, and turn any crooked 
cheese over in the press, leaving them until noon to straighten. 

DRYING, PARAFFINING, AND CURING. 

The cheeses when taken from the press are stenciled with the brand 
and date of making or a reference number, and placed on shelves in a 
well-ventilated room to dry on the surface. This room may be as 
high as 70°. Here they are turned over once a day. 

The cheese should be paraffined when 5 to 10 days old, or pos- 
sibly earher. The parafhii should be at 220° F., at least, and better at 



MISCELLANEOUS OPERATIONS IN CHEESE MAKING. 51 

230° to 250° F. The thinnest possible coat of paraffin is the best, 
and the cheese should be held in the paraflin about 5 secontls and 
then drawn out and left to drain over the vat, on a rack, until it can 
be handled. A thin coating of parafFm is flexible and less likely to 
crack than a thick coating. 

It is ]>ossible to cure this cheese at any temperature between 34° 
and 75°. When it is desirable to cure the cheese as fast as possible, 
a temperature of 75° may be used without injury to the quality. 
However, at this tem}HM'ature there is considerable shrinkage, and it 
is necessary to wipe the cheeses occasionally and turn them over to 
j)revent them from getting moldy and sticking to the shelves. 

At 45° to 55° the cheese cures well, with little shrinkage and a 
minimum amount of labor. It also cures well when stored at 34° 
at the age of 1 week and (levelo)>s little or no mold on the surface, 
but owing to the extra cost this temperature should only be employed 
where it is necessary to hold the cluH'se for a considerable length- of 
time. 

BRANDIN(J AM) SELLING THE CHEESE. 

In order that customers may be sure that they are getting genuine 
pasteurized-milk ch(>es(> when called for, every cheese should be 
nuirked with the words "Pasteurized cheese" running all round the 
edge of the checs(\ All persons making cheese ai'cording to the process 
here described should use such a brand, in order to distinguish this 
j)roduct from the ordinary Cheddar cheese. A large number can 
be rapidly mark(Ml with a rubber stamp or by rolling the cheese over 
rul)ber tyj^c, set in a board, as shown in iigiu'e 2. Narrow strips of 
wood on each side of the board j)revent the cheese from rolling sitle- 
wise otr the type. 

In a new style of pi'oduct ujiiformity is a {|uality which consumers 
and dealers retpiire. It is reconunended that the maker of this stylo 
of cheese keep back one cheese from each day's make, when shipping, 
until the consignment has been accei)ted and ])aid for by the buyer. 
The sample cheese can then be sent along with the next shipment 
without i^lugging. If necessary, the cheese can be phigged with a 
trier, an(l by this means the nuiker will be able to study any faults 
which may be observed by the buyer and avoid them in the future. 
Names of leading chees(^ dealers who have already received sample 
shipments of this make of cheese and found it suitable for their 
trade may be obtamed from the authors. 

Where a maker doubts whether the buyer is giving him fair treat- 
ment, it is recommended that parts of each day's make be sent to 
two different dealers, whose criticisms, if any are received, can be 
compared by the maker at the factory. 



52 



CHEDDAR CHEESE FROM PASTEURIZED MILK, 



TESTING CHEESE FOR MOISTURE WHEN DRESSED IN THE HOOP. 

In making cheese by this process, the green cheese was found to 
differ very Httle in moisture content from day to day, as is shown in 
Table 19. Exceptmg the first day the cheese was made each day in 
two vats, and each vat of curd was tested for moisture separately. 

The determmation of moisture in cheese is not recommended as a 
part of the daily work in a factory. It is of great value, however, 
in experimental work, where it is desired to study the effect on their 
moisture content of different methods of handhng curds, or the effect 
of different moisture content on the market value or keepmg quahty 
of cheese. 




Fig. 2. — Method of markiut; cheese. 

]\loisture tests are easUy made. It is ol)jectionable, however, to 
])lug a new cheese every day for a moisture test because of the dan- 
ger of admitting molds, etc., beneath the rind, and it has been found 
that plugging the green cheese can be entirely avoided by sampling 
it at the tune it is dressed in the hoop, about one hour after puttmg it 
to ]n-ess. The trier hole made at this time by turnmg down the 
bandage and insertmg the trier at the side will close enthely over 
night in the press, leavuig the rind perfect. Samples of cheese thus 
taken from the dressed curd and tested for moisture agreed closely 
in moistiu'e content with samples taken with a trier from the same 
cheese the next day, after pressmg about twenty hours, as may be 
seen from Table 19! 

The moisture tests were all made by heating 10-gram portions of 
the curtl for at least three hours in the Wisconsm high-pressure 



INCREASED YIELD OP CHEESE OBTAINED. 



53 



steam ovon.^ After three or four hours there is practically no further 
loss of weight from samples of fresh curd in 24 hours' heating. Sam- 
ples of cured cheese continue to lose weight with continued heating 
much more noticeably than samples of fresh curd or green cheese. 

Table 19.— Comparison of moisture determinations made on samples talen luhen cheese 
was dressed, three-quarters to one hour after pressing, and on samples taken from green 
cheese, next day, when removed from press. 





Moisture 


content when cheese 


Moisture content. 


le.xt dav. 




Date. 


was dressed. 


when removed from press" 


Differ- 
ence. 




First. 


Second. 


.\verage. 


First. 


Second. 


Average. 


1911. 


Per cent. 


Per cent. 


Per cent. 


Per cenl. 


Per cent. 


Per cent. 


Per cent. 


.\Uf,'. 15 


■.i7. tv) 


37. 40 


37. 5i) 


37. 95 


37. 25 


37. ti:) 


+ 0.10 


Iti 


;is. 50 


3S. 70 


3S. S) 


38. 50 


39. 00 


3S. 75 


+ .15 


Hi 


3S. 50 


3S. 90 


3S. 70 


3S. 05 


3S. 51) 


3S. 27 


- .43 


17 


39. ()(J 


39. 10 


39. 35 


3S. 50 


3S. t) ) 


3S. 55 


— .SO 


17 


3.S. <K) 


39. 00 


3S. 95 


39. 40 


39. 40 


39. 4 ) 


+ .45 


IS 


37. .SO 


37. 75 


37. 77 


37, 75 


37. 95 


37. S5 


+ .08 


IS 


42. 25 


42. 2,5 


42. 25 


41.25 


41.40 


41.32 


- .93 


2:5 


3,S. S!) 


3.S. SO 


3S. ,S.) 


3S. 0,5 


3S. 45 


3S. 25 




23 


42.25 


42. 4.5 


42. 35 


42. 20 


42. 10 


42. 15 


- !2'o 


24 


39. 35 


39. 05 


39. 2!) 


39. 7() 


40. 3 ) 


4 >. 00 


+ ..SO 


24 


44. 25 


44. 3) 


44. 27 


43. 15 


43. 3 ) 


43. 22 


-l.(J5 


2.5 


39. 55 


39. 70 


39. ti2 


.39. 30 


39. 05 


39. 4(1 


- .l(i 


2.') 


44. 10 


44. 45 


44.27 


44. 45 


44. 95 


44. (JJ 


+ ..33 


26 


3S. 95 


39.10 


39. 02 


3S. SO 


39.00 


3.S. 9J 


- .12 


2(3 


44.30 


44. ti!) 


44.45 


42.80 


43.00 


42. 90 


— 1.55 



RESULTS OF TWO YEARS' TRIAL OF THE METHOD. 
INCREASED YIELD OF CHEESE OBTAINED BY THE NEW PROCESS. 



APPARATUS ANO METHODS OF STUDY. 



In the season 1909-1910 it was found that an increased weight of 
cheese is regularly obtained after ])asteurization as comj)aretl with 
the weight obtained by the regular factory methods. For the pur- 
]K)se of accurately studying the yield of cheese in 1911 two scales 
were used, one of 5,000 ])ounds' capacity graduated on the beam to 
one-half pound and one of oOO i)ounds' caj)acity graduated on the 
beam to one-tenth })Ound. The larger scale was set uj) permanently 
in one corner of the make room, and a woodcui frame carrying a 300- 
galion steel receiving vat was placed upon it. The outlet of the vat 
is of sanitary metal ])i|)ing, suspended by wire to the vat m such a 
way that the ])ipe and contents are weighed each time \vith the vat. 
The frame, vat, and pipe w^eighed 487 V pounds when empty. The 
separate weights and the scale on the beam were carefully tested by 
use of test weights. The entii-e set of w^eights agreed among them- 
selves so closely that no difference could be detected in the equilibrium 
of the beam when one weight was substituted for another in weighing 
a load. The error in a smgle weighing is not over one-iiutirtcu- of a 

' Farringtou, E. H. A creamery method for the determination of water in butter. Wisconsin Agri- 
(ultural Experiment Station, Bulletin 154. Madison, Sept., 1907. 



54 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

pound with large or small loads. Except when weighmg the lever 
is kept up, thus relievmg the knife edges from load and wear. 

The method of using this apparatus is as follows: The vat bemg 
empty with the ])ipes in place and stopcocks closed, the supply of 
milk is run into the vat through a conductor and cloth strainer. The 
strainer and conductor are then removed, the lever is lowered, and 
the weight of vat and contents determined. It is our habit to balance 
the scales exactly, giving neither "up" nor ''down" weight. The 
lever is then raised, and the operator clmibs up tlio ladder on the 
frame to the riml)oard along the side of the vat. With a dipper he 
stms the milk continuously and vign'ously for 5 or 10 mmutes, and 
contuiues stirring while a portion of the milk is being drawn out for 
use in one of the experimental cheese vats. The vat and the remam- 
ing milk are then weighed with the same precautions as before, after 
which another portion of the milk may be tlrawn off for use in another 
vat in the same manner. 

Tlic ])rocautions mentioned above seemed sufiicient to insure that 
the milk used in the two vats — one for ordinary and one for pas- 
teurized cheese — was thoroughly mixed at the time it was drawn 
from the receiving vat, and that each lot was weighed accurately 
with a total possible error of not over one-half a pound in a vat of 200 
to 2,000 pounds of milk — an error of one-fortieth to one-fourth of 
1 per cent, at most. 

The other new scale mentioned above is a counter scale gradiuited 
on the beam to one-tenth of a pound and sensitive to one-twentieth of a 
pound with any load uj) to 200 poimds. This was used for weighing 
the cheese throughout the work here described. The set of weights 
used with this scale agreed among themselves and with the test 
weights mentioned above in the description of the other scale. 

With the smaller scale, 20 to 200 pounds of cheese could readily be 
weighed with an error of not over 0.05 of a pound, or 0.25 per cent, 
at most. On 6S days durin^ij the season of 1911 the receiving vat of 
milk was divided into two accurately weighed portions for this ex])er- 
iment. One of these was pasteurized and made up into cheese by 
the new method, the other portion was made up into cheese by regidar 
factory methods. The cheese was 13^ inches in diameter by 4 inches 
high, the "daisy" size. The green cheese was always weighed as 
quickly as possible after being removed from the hoops. The daily 
record of weights of milk used and of cheese obtained, and the per 
cent of increased yield which resulted from pasteurization, are shown 
in Table 20. 



INCEEASED YIELD OF CHEESE OBTAINED. 



bi> 



Table 20. — Increased yield of green eheese obtained by the 7iew method from pasteur- 
ized milk. 







Pasteurized milk. 




Raw milk. 


I'r 


port ion of 


















St 


irter used. 














Gain by 






Dale made. 






Yield of 






Yield of 


pasteur- 














clieese 






cheese 


ized y, 
milk. '; 










Milk 


(1 reon 


per liun- 


Milk 


Green 


per hun- 


s- 

ir- K 








use J . 


cheese. 


dred- 


used. 


eheese. 


dred- 


lei 

iZL 


aw. 










weight 






weiglit 


d. 












of milk. 






of milk. 








1911 




Pounds. 


Pounds. 


Pounds. 


Pounds. 


Pounds. 


Pounds. 


Per cent. Per 


ct. Per ct. 


Feb. 


Zi 


538. 


53. 20 


9. 89 


3S0. 


35.40 


9.31 


6.23 


75 


00 




24 


504. 5 


51.00 


10.11 


380.0 


36. 60 


9.63 


4.98 


75 


00 




27 


l,02ii.5 


108. 20 


10.35 


600. 


57.80 


9.63 


7.48 


75 


00 




28 


800. 


82. 20 


10.27 


400.0 


38. 30 


9.57 


7.31 


75 


75 


Mar. 


1 


.350. 


35.40 


10.11 


510.0 


50.20 


9.84 


2.75 


75 1 


50 




2 


389. 5 


39.00 


10.01 


628.0 


59.70 


9.51 


6.61 


75 






3 


340. 


35.00 


10.29 


522.0 


52.30 


10. 02 


2.79 


75 1 


.50 




7 


8.55. 


88. 20 


10.32 


380. 


38. 40 


10.11 


2.08 


75 2 


(M) 




S 


590. 


60. 70 


10.29 


388. 5 


39.30 


10. 12 


1.68 


75 1 


50 




9 


41S.0 


42.80 


10.24 


417.5 


41.00 


9. 82 


4.27 


75 1 


00 




10 


442.0 


44.70 


10.11 


700.0 


66. 40 


9.49 


6. 5:3 


75 


00 




13 


1,166.0 


122.00 


10.46 


275. 


25.70 


9. 34 


12,00 


75 


00 




14 


956.0 


10.3.40 


10.81 


260. 


25.80 


9. 92 


8.97 


75 


75 




15 


570.5 


.5,8. 10 


10. 18 


380.0 


37.50 


9. 87 


:3. 14 


75 


75 




K) 


.531.5 


56.90 


10.71 


359.0 


37. 40 


10. 42 


2.78 


75 2 


(M) 




17 


395. 


41.20 


10.43 


396. 


39. 80 


10. 05 


3. 78 


75 2 


50 




20 


1,.$44.0 


136. 00 


10. 12 


384. 


36. 60 


9. 53 


6.19 


75 


00 




21 


570.0 


56. 40 


9.89 


378. 


35. 30 


9. 34 


5. 89 


75 


00 




22 


3ii2. 5 


36. 00 


9. 93 


542.0 


51. ,80 


9.56 


3. .87 


75 1 


67 


.\pr. 


.5 


5S5. 


()0. 80 


10.39 


390. 


37. 70 


9. 67 


7.45 


75 


75 




7 


508. 


51.15 


10.07 


339. 5 


32. 50 


9.57 


5.22 


75 


75 




11 


549. 


55. 00 


10. 02 


549. 


52. 60 


9. 58 


4.59 


75 


75 




13 


364. 


35. 70 


9.81 


364.0 


34. ,55 


9.49 


3. 37 


75 


75 




17 


800. 


80. 25 


10. 03 


6(X). 


55.50 


9.25 


8. 43 


75 


00 




IS 


720. 


71. 15 


9.88 


540. 


49. .80 


9.22 


7.16 


75 


00 




24 


1.254.0 


122. .80 


9.79 


660. 


61.90 


9.38 


4.37 


75 


75 




27 


570.0 


55. 30 


9.70 


380. 


:55. 70 


9.39 


3. 30 


75 


75 




28 


420. 


40. 85 


9.73 


420.0 


40.05 


9.54 


1. 99 


75 


75 


May 


2 


636. 


65. 0.5 


10.2:3 


424.0 


42. 00 


9.91 


3.2:3 


75 


75 




3 


558. 


54. 30 


9. 73 


372.0 


35.55 


9.56 


1.81 


75 


75 




8 


1.693.0 


1.58. 15 


9.34 


800. 


70. 95 


8.87 


5. 30 


75 


75 




10 


798. 


77. (;o 


9.72 


798.0 


73. 70 


9.24 


5.19 


75 


75 




15 


1,. 587.0 


161.60 


10. 18 


800.0 


76.90 


9.61 


5. 93 


75 


75 




17 


1.088.5 


109. 00 


10.01 


800.0 


76.60 


9. 57 


4.60 


75 


75 




22 


1,223.0 


129. 40 


10.58 


800. 


78. 20 


9.77 


,8.29 


75 


75 




2.5 


851.0 


.87. 00 


10. 22 


800. 


78.80 


9.85 


3.76 


75 


75 




29 


1,315.0 


138. 60 


10. 54 


800. 


SO. 20 


10.02 


5.29 


75 


75 


June 


I 


798. 


83.50 


10.46 


800.0 


83. 10 


10. .39 


.67 


75 


75 




2 


799. 5 


82.85 


10. 36 


800.0 


79.50 


9.94 


4.23 


75 


75 




7 


790. 5 


79.65 


10.07 


800.0 


76.60 


9.57 


5.22 


75 


75 




9 


800. 


82. 30 


10.29 


800.0 


78.15 


9.77 


5. 32 


75 


75 




13 


1,090.0 


119. 70 


10.98 


800.0 


80. 20 


10.02 


9. 58 


75 


00 




15 


795. 


85.50 


10.75 


800.0 


80.70 


10.09 


6.54 


75 


75 




16 


800. 


8.3.45 


10. 43 


800.0 


78. 95 


9. .87 


5.67 


75 


75 




19 


810.0 


87.60 


10.81 


800.0 


79. 65 


9.96 


8.54 


75 


00 




21 


798. 5 


81.75 


10.24 


800.0 


77.70 


9.71 


5.46 


75 


75 




26 


770.0 


,80.65 


10.47 


770.0 


75.45 


9.80 


6.84 


75 


00 




27 


801.0 


83.50 


10.42 


800.0 


79.00 


9. 88 


5.46 


75 


75 




28 


801. 5 


85.90 


10. 73 


SOO. 


82.00 


10.25 


4. 68 


75 


75 


July 


3 


1,2.34.0 


122. 75 


9.95 


.800. 


72. 35 


9.04 


10. 07 


75 


00 




6 


995.0 


102. 4.5 


10.30 


()60. 


66. 10 


10. 02 


2.79 


75 


75 




8 


1.068.0 


108. 50 


10.16 


660. 


62. SO 


9.52 


6.72 


75 


00 




10 


1,064.5 


107. 30 


10.08 


800.0 


74. 35 


9.29 


8.50 


75 


00 




11 


914.0 


93. 50 


10.2:3 


660.0 


63. 6.5 


9.64 


6.12 


75 


00 




12 


873. 


93. 15 


10.67 


800.0 


78. 20 


9.77 


9.21 


75 


75 




24 


1,195.0 


12.5. 10 


10.47 


600.0 


58.20 


9.70 


7.94 


75 


75 




26 


1,099.0 


lis. .32 


10.77 


190.0 


19.32 


0.17 


5. 90 


75 


00 


Aug. 


29 


294.5 


31.58 


10.72 


290.0 


30.50 


10.52 


1. 90 


75 


75 




30 


344.0 


35.82 


10.41 


340. 


34.05 


10.01 


4.00 


75 


75 


Sept. 


1 


322. 


34.10 


10.59 


320.0 


32.60 


10.19 


3.92 


75 


75 




5 


291.5 


31.00 


10. 63 


292.0 


29.65 


10.15 


4.73 


75 


75 




6 


276. 


28.95 


10.49 


275. 


27.20 


9.89 


6.40 


75 


75 




7 


286. 5 


31. 03 


10. 83 


286.5 


29.48 


10.29 


5.24 


75 


75 




8 


292.0 


31.50 


10.79 


292.0 


30.25 


10.36 


4.14 


75 


75 




20 


263. 


29.15 


11.08 


263. 


27.80 


10.57 


4. .82 


75 


75 




22 


265.0 


29.20 


11.02 


266.5 


28.05 


10.52 


4.75 


75 


75 




25 


748. 


a3. 90 


11.22 


250.0 


26.40 


10.56 


6.2.5 


75 


75 


Oct. 


2 


700. 5 


79.25 


11.31 


420.0 


4.5.10 


10.74 


5.31 


75 


75 


Avera 


3 
?e. . 


251.0 


27.75 


11.05 


250.0 


26.25 


10.50 


5.24 


75 


75 






10. 7 






9.815 


5.374 



















"I" 1 



56 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

It wHl bo noted that every day iii the season there was a greater 
yield of cheese from the pasteurized milk. From 250 to 1,700 pounds 
of milk were handled in each vat. The average yield of green cheese 
from raw milk was 9.815 pounds and from pasteurized milk 10.537 
pounds per hundred pounds of milk. 

The daily increase in yield ranged from 0.6 per cent to 12 per cent, 
and m 50 cases (72 per cent) lay between 3 and 8 per cent, while the 
average mcrease in yield by the new process on 69 days was 5.37 per 
cent.^ On 45 days the same proportion of skim milk starter — three- 
fourths per cent — was used in both the raw and the pasteurized 
milk. In the raw milk none ■\\as used on 16 days, and on 8 daj's 
1 to 2^ per cent (on the average 1.71 per cent) was used, while in 
every case the pasteurized milk received three-fourths per cent 
starter. If the use of starter affects the yield of cheese, the average 
yield from the pasteurized milk on 16 days was raised about three- 
fourths per cent, while the average yield from raw milk was raised 
on 8 days about 1.71 ])er cent. These two effects offset each other 
in the table, giving a slight advantage to the yield from the raw milk, 
so that the fmal average figin-e — 5.37 per cent — representing the aver- 
age gain in yield of green cheese by the new process, is no higher and 
possibly a trifle lower than it would have been if equal proportions of 
starter had been used in all cases. 

Among the 17 cases m Table 20 in which no starter was used m the 
raw-milk vat, the average gam m the pasteurized-milk vat, usmg 
three-fourths per cent starter, was 7.48 per cent; and in 8 cases where 
more than three-fourths per cent starter was used in the raw milk, the 
average gam in yield in the pasteurizod-milk vat was 3 i)er cent. 
From this it would appear that the proportion of .starter used does 
notably afl'ect the yield of cheese, conti-ary to some recent statements.^ 

SEARCH FOR SYSTEMATIC ERRORS IN EXPERIMENTS ON YIELD OP CHEESE. 

The presence of systematic errors was carefully guarded against in 
the daily work on the yield of cheese. Before dividmg the milk from 
the receivmg vat for use in the two make vats, the milk was first 
thorouglily stirred for 4 to 10 mmutes, as already stated, and the stir- 
ring was contmued while the milk was running out. The portion of 
milk drawn out first was commonly used for making the raw-milk 
cheese, but sometimes, as on March 8, 9, 10, 17, 21, 22, and April 7, 
11, 17, 18, and May 10, the portion drawn first was used for making 
the past.urized-milk cheese. The average gain m yield through pas- 

1 Both the median and the mode lie between 5 and 6 per cent. The mode is the class which occurs with 
the greatest frequency; the median is the magnitude at the middle of the series from largest to smallest. 
See "Statistical Methods," by C. B. Davenport, New York, 1899, or •' Principles of Breeding," by E. Daven- 
port, Boston, 1907, p. 6S4. 

2 Van Slyke, Lucius L., and Publow, Charles A. The science and practice of cheese making. New York, 
1909. See p. 69. 



INCREASED YIELD OF CHEESE OBTAINED. 57 

teurizatioii on these 11 days was 5.15 i)er cent, so nearly equal to the 
general avcn^igo of 5.37 ])er cent (see Table 20) as to indicate that the 
gain in yield is not due to any difference in composition of the milk 
when divided into two lots. Carefully tested thermometers and the 
same pair of curd laiives were used in every vat. 

Usually tlie vat of pasteurized milk was set first with rennet, and 
the vat of raw milk 5 minutes later. The two vats were placed near 
each other, and conditions were such tliat one operator could stir 
them both at once, if desired. On 11 ihiys, April 18, 24, 27, May 8, 
10, 15. 17, August 29, 30, Soptem})er 1, and October 2, the rennet was 
ackled to the raw milk first, and to the ])asteurized milk 5 minutes 
later. The average gain in yield on {]u\ 11 (hiys was 4.63 per cent, 
indicating that the order of setting the vats had nothing to do with 
tlie gain m yield. 

In order to ascertain what per cent of miavoidable error enters into 
the measurement of yield of cheese, a special experiment was performed 
on 34 days. Eacli day, with all of the usiuil precautions, two lots 
of milk drawn from tlie receiving vat were run through the pasteurizer, 
one after the other, and made up into cheese in separate vats marked 
(C) and (D) standing near each other, and handled by the same oper- 
ator (^Ir. Bruhn). The vats were heated and set exactly 5 minutes 
a])art by the watch, and the time schedule for each vat was strictly 
followed m every detail. The same curd knives and thermometer 
were used in both vats. 

The pasteurizer and cooler are always rinsed with hot water at the 
beginnmg of the first run, but are wet with adhering milk at the close 
of the run just before beginning the second run. Thus the actual 
weight of milk m the fii'st vat might be slightly less than it shoidd be. 
To avoid this source of error, the pasteurizer and cooler were allowed 
to drain each tune into the vat for several minutes (until the stream 
of milk broke into suigle drops), and then the metal surfaces were 
carefully rmsed with two measured portions of clean water. Thus 
the siu'faces of the i)astem'izer and cooler were w^et with w^ater at the 
beginning of the second nm as well as the fu'st. The milk content 
of the rinsmg's (see Table 21) was found to be very small and uniform, 
amounting to about 0.8 of a ])oimd of milk each time, which if it were 
all lost from one vat but not tlie other would cause a diiference of 
yield of cheese from a 500-pound lot of milk (as in Table 22) of 
about 0.16 i)er cent. In order to avoid this source of error entirely, 
the rinsings from both runs were either thrown away, as on the first 
15 days listed in Table 22, or the rinsings after each run were added 
to the respective vats, as on the last 19 chiys. 



58 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 
Table 21. — Milk content of rinsings of pasteurizer and cooler. 



Date. 


Weight 
of rins- 
ings. 


Fat content. 


Estimated 
weight of 
cheese in 
rinsmgs. 


Estimated 
\vei'.;h1 of 
milk in 
rinsings. 


Percent. 


Weight. 


1911. 

Apr. 2.-. (Vat C) 

2.5 (Vat D) 

2(i(Vat(') 

2li(Vat D) 


Pounds. 
2.25 
2.25 
2.25 
2.25 


1.25 
1.25 
1.20 
1.20 


Pounds. 
0. 028 

. 028 
.027 
.027 


Pounds. 

0.08 

.08 

.08 

.08 


Pounds. 

0.8 
.8 
.8 
.8 



The yield of cheese obtained in diipUcate vats thus handled was 
never exactly equal and varied on the average for 33 days by 0.585 
per cent of the weight of the cheese, as shown in Table 22. The milk 
in Vat C was drawn first from the receiving vat, and was pasteur- 
ized and set first in all cases except where otherwise noted. 

Table 22. — Variation in ijiehl of cheese from duplicate rats of pasteurized milk. 







Vat C. 




Ratio of 




Vat D. 




Differ- 
ence in 














Date. 


\V('ii,dit 


Weight 


Cheese 


n;ilk 
\voi':''hts. 


Weight 


Weight 


Chee.se 


yield of 
the two 

vats. 




of 1, ilk 


of green 


per cwt. 




of milk 


of green 


per cwt. 




u.sed. 


cheese. 


of milk. 




used. 


cheese. 


of milk. 










Ta< TV;/ 










1911 


Pounds. 


Pounds. 


Pounds. 


C. D. 


Pounds. 


Pounds. 


Pounds. 


Per cent. 


Mur. 23 


430. 


42.50 


9. 884 




430. 


42.55 


9. 895 


0.11 


24 


390. 


38.80 


9. 949 




390. 


39.10 


10. 026 


.77 


27 


375. 


3(5. 10 


9.627 




1,125.0 


109. 20 


9. 707 


.83 


28 


350. 


3(5. (50 


10.457 


1 21 


875. 


92.20 


10. 537 


.76 


29 


585. 


59. 10 


10. 102 


1| l' 


390.0 


39.45 


10.115 


.13 


yo 


495. 


50. 10 


10.121 




330. 


33.50 


10. 151 


.30 


:u 


.540. 


54.20 


10. 038 


ll 1 


360.0 


36. 15 


10. 042 


.04 


Apr. 4 


5S5. 


00. 50 


10. 342 


ll 1 


390.0 


40.55 


10.397 


.53 


(i 


534. 


54.15 


10. 140 


li 1 


35(i. 


37.35 


10. 491 


1 3. 46 


1(1 


1 , (ISO. 


10(5. 30 


9. 842 




360. 


.35. 65 


9. 903 


.(52 


12 


555. 


55.70 


10. 036 


J I \ 


370. 


37. 60 


10. 162 


1.25 


14 


380. 


38. 10 


10. 026 




380. 


38.40 


10. 105 


.79 


19 


400. 


40. 30 


10.075 




JOO. 


40.60 


10. 150 


.74 


20 


370. 


3(5. 75 


9. 932 


1 1.^ 


55 .. 


55. 40 


9. 728 


.50 


21 


380. 


37. 00 


9.737 


1 \\ 


570 


55. 45 


9.728 


.09 


25 


420.0 


41.00 


9. 762 




4:::0. 


40. 90 


9. 738 


.25 


2(1 


370. 


3(5. 20 


9. 784 


1 \\ 


555. 


54.35 


9.793 


.09 


May 4 


420. 


42.10 


10. 024 




420.0 


42.50 


10.119 


.95 


5 


531.0 


51.40 


9. 680 


1 .', 1 


354. 


34.35 


9.703 


.24 


9 


408. 


40. (55 


9. 963 


1 1 ', 


612. 


60.80 


9. 935 


.28 


11 


410.0 


41.. 50 


10. 122 




410.0 


41.80 


10. 195 


.72 


12 


795. 


78. 25 


9. 843 




795.0 


79.50 


10. 000 


1.59 


Iti 


800. 


80. 30 


10.037 




800. 


80. 65 


10.081 


.44 


18 


(iOO. 


03. 80 


10. (533 




600. 


62.70 


10. 450 


1.75 


19 


(iOO. 


62.20 


10. 367 




600. 


61.95 


10.325 


.41 


2:-! 


000. 


04. 00 


10. 667 




600. 


63. 75 


10.625 


.39 


24 


012.25 


64.35 


10.510 




612.25 


65.15 


10.641 


1.24 


30 


600. 


61.30 


10.217 




600. 


60.75 


10. 125 


.91 


31 


(iOO. 


62.10 


10.350 




600. 


62.12 


10. 353 


.03 


Juna C 


583. 


59. 15 


10.146 




577. 75 


59.15 


10. 238 


.91 


H 


000. 


61.55 


10. 258 




600. 


61.85 


10. 308 


.49 


14 


000. 


62.28 


10. 380 




600. 


(52. 15 


10. 358 


.21 


17 


599. 5 


62.71 


10. 460 




599. 5 


63.11 


10.527 


.(54 


20 
Average. . 


(500. 


60.30 


10. 050 




■ 600. 


60.90 


10. 150 


.99 


535. 22 




10. 105 




536. 37 




10. 149 


1.585 







1 Tlie result for Apr. 6 is omitted in computmg the average because of abnormal conditions. 

Among the 34 days' results obtained during the season, as shown 
in Table 22, tlie difference in yield between duplicate vats exceeded 
1.75 per cent in only one case. On this day there was unusual 
diJhculty in the work because of unexpected failure of the supply of 



DISCUSSION OF VARIATION IN YIELD. 59 

water for cooling, and, although the dh-ect cause of the exceptionally 
liigh figure (3.4(3 per cent) can nob be directly traced, it seems likely 
that some gross error occurred, whicli was avoided on the other days. 
Therefore this figure (for April 0) is omitted from the general average. 

On 28 days (82 per cent of all cases) the variation in yield between 
du[)licate vats lay below 1 per cent and on 33 days (omitting April G) it 
a^'eraged 0.584 per cent. For present jiurposes, therefore, it may be 
considered tliat the figure 5.37 per cent, from Table 20, representing the 
average increuscnl yield of green cheese obtained through pasteuriza- 
tion, is correct within 0.58 i)er cent, or about one-ninth of its value. 

The yield of cheese from ])asteurized milk is thus capable of meas- 
ui-emont with an average dilFcu'ence between duplicate determina- 
tions of O.G \)vv cent of the amount determined. This degree of 
accuracy in manii)ulation is compara])le with liiat attained in many 
analytical chemical process(\s, in wliich n limit of 1 ])er cent of the 
amount determined is commonly set as tlie maximum allowable 
differenci^ between (hiplicativs. 

The ])rin<'ii)a] cause for the difference of O.GO ])er cent in the yield in 
making du])li('at(> vals of cheese docs not Yw in the weighing of the 
milk or cheese, because witli llic seal's eni])loye(l both the milk used 
and tfu^ chees(^ obtained thei'efi'om could \)o weigiu'd with an (UTor 
of not over 0.10 ])ei' cent. Tiie ])er cent of difl'ereuce in yield was not 
reduced when the W(>ight of milk handled was increascul. It appears 
likely, therefore, that there ar(^ small unavoidable difi'erences caused 
by the size of the cubes or in th(> mani])ulati()n of the milk and curd 
which cause an average difference in yield of from 0.50 to O.tiO ])er 
C(^nt between du])licate ^•ats. 

An efl'oi't was made so fai- as tini(^ ))erniitted to determine whether 
any one of several causes was r(>gularly or ejiiefly responsible for this 
average difference in tlu^ yield. The stirring of the vats was done 
by hand in all eases when^ the weight of milk in a vat was less than 
400 pounds. For ex])eriments with 400 to 800 ])oun(ls of milk in a 
vat a pair of vats of 800 ])ounds capacity was used. These were 
stirred with a ])air of wixxIcmi rakes, exactly alike in sha])e and size. 
Larger c^uantities of milk than 800 pounds were always handled in a 
vat of 2,400 })ounds ca])aeity in which a two-bladed rotating and 
oscillating agitator was used instead of the rake. The difference 
hi yield between duplicate vats could not be traced to the methods 
of stirring. Thus, on March 27, the agitator-stirred vat (D) gave 
0.83 per cent greater yield than the hand-stirred vat (C), but on 
April 10 the hand-stirred vat (I)) gave 0.62 per cent greater yield 
than the agitator-stirred vat (C). The average difference on 12 
days in yield l)etween du])licate rake-stirred vats was 0.70 per cent, 
and the average difference in yield between duphcate hand-stirred 
vats on 19 days was 0.52 per cent. The differences varied slightly 
whatever method of stirring was employed. 



60 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



Again, handling different amounts of milk did not appear to affect 
the yield in duplicate vats. On 12 days, using one and one-half to 
three times as much milk in one vat as in the other, the average differ- 
ence in yield was 0.40 per cent, which is a little smaller than the 
average of the other days, showing that the quantity of milk handled 
by this method does not affect the yield. Since the same results are 
obtained in a small A^at with 375 pounds of milk as m a large one 
with 1,125 pounds of milk, it is believed that the general results of 
this investigation are applicaljle to the largest sized vats of milk used 
in factories. 

SHRINKAGE BEFORE PARAFFINING, AND YIELD OF PARAFFINED CHEESE. 

Since there is always some loss in weight of cheese previous to 
paraffining, it is of interest to comj-yare the shrinkage of ordinary 
cheese with that of new-process cheese, and to determine whether 
there is an increased yield of pasteurized-milk cheese when paraffined 
corresponding to the increased yield observed in the same cheese 
when green. This can be done readily from Table 23, which shows 
the average results for the season and also the range of daily variation. 

Table 23.- — Comparison of old and new process cheese as to shrinkage before paraffining 
and yield of paraffined cheese. 







ShrinkaR 


; per 100 












pounds 


of green 


Yield per 100 






Age 


elieese 


before 


pounds 


of milk. 


Gain in 


Date 


wlien 


paraflinins;. 






yield 


made. 


par- 
affined . 










by new 
process. 


Pasteur- 
ized. 


Raw. 


Pasteur- 
ized. 


Raw. 


1911. 


Dans. 


Pounds. 


Pounds. 


Pounds. 


Pounds. 


Per cent. 


Feb. 23 


It) 


5.92 


5.23 


9.30 


8.83 


5.32 


24 


18 


5.98 


5.05 


9.50 


9.14 


3.94 


27 


15 


5. 32 


4.07 


9.79 


9.18 


6. 04 


28 


14 


5.23 


4.57 


9.74 


9.14 


6. 51) 


Mar. 1 


13 


5. 30 


4.88 


9.57 


9.30 


2.24 


2 


12 


5. 20 


4.35 


9.49 


9.09 


4.40 


3 


15 


5.71 


5.35 


9.71 


9.48 


2.43 


7 


11 


5.21 


4.43 


9.78 


9.06 


1.24 


8 


10 


4. 45 


4.58 


9.83 


9.65 


1.80 


9 


9 


5. 49 


4.82 


9. 08 


9.35 


3.53 


10 


8 


3. .58 


3.35 


9.75 


9.17 


0. 32 


13 


12 


5.08 


4.28' 


9.03 


8.95 


10. 95 


14 


11 


5. 13 


4.20 


10. 20 


9.50 


8.00 


15 


10 


3. 90 


3.73 


9.78 


9. m 


2.95 


l(i 


9 


4.22 


3. 01 


10. 25 


10. 04 


2.09 


17 


8 


3. 88 


,3.27 


10.03 


9.72 


3.19 


20 


12 


5.37 


4.37 


9.58 


9.11 


5.16 


21 


11 


4.42 


3.08 


9.40 


8.99 


5.23 


22 


10 


4.72 


3.86 


9. 46 


9.19 


2.94 


Apr. 5 


10 


4. 30 


3.58 


9.94 


9.32 


6. 65 


7 


8 


4.10 


3.85 


9.66 


9.20 


4.00 


11 


10 


5.09 


4.56 


9.51 


9.14 


4.05 


13 


8 


4.02 


4.05 


9.35 


9.11 


2. 63 


17 


12 


5.11 


4.23 


9.52 


S.80 


7.45 


18 


11 


4.85 


4.42 


9.40 


8.81 


0. 70 


24 


12 


5.05 


4.11 


9.30 


8.99 


3.45 


27 


9 


3. 98 


3. 64 


9.32 


9.05 


2.98 


28 


8 


2.82 


2. 02 


9.45 


9.29 


1.72 


May 2 


11 


4. 30 


3.93 


9.79 


9.52 


2.84 


3 


10 


4. 33 


4.08 


9.31 


9.17 


1.53 


8 


13 


4. 52 


4.05 


8.91 


8.40 


5.32 


10 


11 


4.19 


3.73 


9.32 


8.89 


4.83 


15 


12 


4. 04 


4. 36 


9.71 


9.19 


5.65 


17 


10 


4.57 


3.98 


9.49 


9.19 


3.26 


22 


12 


4.71 


4.09 


10.08 


9.37 


7.57 


25 


11 


4.71 


3.93 


9.74 


9.46 


2.96 


29 


13 


4.72 


4.37 


10.04 


9.59 


4.09 



COMPARISON OF SHRINK Ar4E BY OLD AND NEW PROCESSES. 61 

Table 23. — Comparison of old and neiv pmccsa cheese as In shrinhicje before paraffining 
and yield of paraffined cheese — Continued. 







Shrinkage per 100 












pounds of green 


Yield 


per 100 






Age 


cheese before 


pound.s 


of milk. 


(iain in 


Date 


when 


paraffining. 






yield 


made. 


paraf- 
fiued. 








by new 
process. 














Pasteur- 
ized. 


Raw. 


Pasteur- 
ized. 


Raw. 




1911. 


Days. 


Pounds. 


Pounds. 


Pounds. 


Pounds. 


Prr cent. 


Juno 1 


10 


3.92 


3.t;7 


10.05 


10.01 


0.40 


2 


9 


4.22 


3.92 


9. 93 


9. ,'•.5 


3. 98 


7 


7 


4.21 


3. 66 


9. 6(i 


9. 22 


4.77 


9 


S 


3.80 


3. .W 


9.90 


9. 12 


5. 09 


13 


10 


5. 26 


4.74 


10. 40 


9. .'5 


8. 90 


15 


8 


4.49 


3. 82 


10. 18 


9. 70 


4.95 


16 


7 


4.43 


3. 64 


9. il7 


9.51 


4.84 


19 


12 


4. 85 


4.27 


10. 29 


9. 53 


7.97 


21 


10 


4.46 


4. IS 


9. 7S 


9.31 


5. 05 


26 


12 


4. ,'53 


4.17 


10. 00 


9. 40 


6. .38 


27 


n 


4.19 


3. SO 


9. 99 


9. r,i) 


,5. 16 


2S 


10 


4.02 


3.41 


10. :«) 


9. 90 


4.04 


July -i 


It 


4. ,16 


3.91 


9. 49 


8.1.9 


9.21 


c, 


11 


4.20 


4.01 


9.8(i 


9. 61 


2.(i0 


s 


9 


3.fi4 


3.42 


9.79 


9. 19 


6.53 


10 


10 


4. .SO 


4.64 


9. 60 


8. S6 


8. 35 


11 


11 


4.46 


4.01 


9.77 


9. 26 


5. 51 


12 


10 


4. .54 


3. (15 


10. 19 


9. 42 


8.17 


Aug. 29 


11 


4.99 


(i.07 


10. 18 


9. 88 


3.14 


.30 


10 


4. 22 


4. 05 


9. 97 


9. 61 


3.75 


Sept. 1 


8 


4.14 


4. 14 


10. 15 


9.77 


3.89 


r^ 


13 


4.35 


4. 05 


10.17 


9. 74 


4.42 


6 


12 


3.82 


.3. 49 


10.09 


9. 54 


5.(i5 


7 


11 


3. 49 


2. 99 


10. 45 


9. 98 


4.71 


8 


10 


3. 17 


2.81 


10. 45 


10. 07 


3.77 


20 


10 


3. SO 


3.41 


10. 66 


10.21 


4.41 


22 


8 


3. 43 


3.21 


10.64 


10. 19 


4.42 


25 
Average.. 


16 


6. 49 


5. 87 


10.49 


9.94 


5.53 




4. 546 


4.078 


9. 833 


9. 3S8 


4.761 







In practically every case in Talile 23 tlie pasteurized-milk cheese 
sliowcd a o;roator slirinkage tliaii the raw-milk clieose durinf? the period 
before paraffining, which was 7 to 19 days. The average shrinkage 
of raw-milk cheese before parafhniiig, for all G5 cases, was 4.08 
pounds per hundred of green cheese, and for the pasteurized-milk 
cheese it was 4.55 pounds per hundred, nearly one-eighth greater 
than the raw. This excess shrinkage is observed whether the cheese 
was paraffined at 7 or 14 days, as is show^n in the following table, 
which is a summary of Table 23. 

Table 24. — Shrinkage of cheese when paraffined at different ages (surnnmrg of Table 2o). 







Average shrinkage in 










weight per 100 










pounds green cheese. 






Age when 
paraffined. 


Cases av- 




Excess in i 


asteurizcd. 
















Pasteur- 
ized. 


Raw. 
















Per cent of 


Days. 


Number. 


Pounds. 


Pounds. 


Pounds. 


raw. 


7 to 8 


11 


3. 95 


3. .i6 


0. 39 


11 


9 


,■■, 


4.31 


3. S8 


.43 


11 


10 


10 


4.35 


3. 83 


.52 


13 


11 


12 


4.52 


4.10 


.42 


11 


12 


10 


4.84 


4.17 


.67 


16 


13 to 19 


11 


5.29 


4.78 


.51 


11 



62 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



On account of this excess shrinkage before paraffining, amounting 
to about one-half pound per hundred pounds of cheese, the average 
increased jneld of 5.37 pounds per hundred of milk observed in the 
pasteurized cheese when green (Table 20) was reduced to 4,76 pounds 
(see Table 23) by the time the cheese was paraffined. 

SHRINKAGE AND YIELD OP CURED CHEESE. 

The further shrmkage and yield of cheese after paraffining was 
studied: (1) With cheese cured at Madison, Wis., at a temperature 
of 60° to 75°; (2) with cheese cured at New Orleans, La., and weighed 
both at New Orleans ^ and Madison; (3) with cheese cured at New 
Orleans or at Columbus, Ga., and weighed both at Chicago and at 
IVIadison; (4) with cheese cured in a warm room at Madison; and (5) 
with cheese put in cold storage at 34° F. at Waterloo, Wis., at difl"er- 
ent ages after paraffining. So far as possible duplicate cheeses from 
the same days' make were cured in the different ways stated. 

These different methods of curing were chosen for study as repre- 
senting (1) curing conditions at Wisconsin factories; (2), (3), and (4) 
conditions to which annually large amounts of cheese are subjected 
when shipped south for sale; and (5) when cured in cold storage as 
commonly practiced by dealers. 

The shipments to New Orleans were sent on four dates between 
April 29 and July 24, 1911. Each shipment consisted of 9 to 25 
pasteurized-milk cheeses, and an equal number of raw-milk cheeses 
for comparison. In order that the cheese stored might be as repre- 
sentative as possible, each pair represented a different day's make. 

For each lot of cheese shipped away from Madison for storage, a 
duplicate lot from the same days' make was kept at Madison. The 
method of designating these different lots of cheese is shown in 
Table 25: 

Tabte 25. — Reference numbers to different lots of cheese stored in 1911. 



Date made. 


Cheese 

Nos. 


Cured at 
Madison. 


Cured at 
New Or- 
leans. 


Cured at 
New Or- 
leans and 
Columbus, 
Ga. 


Cured in 
warm room 
at Madison. 


Cured at 

Waterloo, 

WLs. 


Feb. 23 to Apr. 16.... 

Apr. 24 to May 17 

May 22 to June 16 

June 19 to July 12.... 
July 13 to Aug. 21...- 


171 to 207 
211 to 227 
230 to 246 

248 to 2G3 
264 to 283 


lA 

2A 

3A 

4A 

5A 


IB 








2B 








3B 

41? 


3C 

4C 


3D .. 




4D 








5E 











In addition to weighing each cheese separately they were also 
weighed in lots of five, and the close agreement of the weight of a lot 

1 The details of the work at New Orleans connected with the storage, weighing, and shipping of the 
cheese used in this test were handled by Mr. W. J. Bleecker, junior dairyman of the Dairy Division, 
Bureau of Animal Industry. Thanks are due to Mr. Bleecker for his very careful attention to this work. 



CURING VAEIOUS LENGTHS OF TIME. 



63 



of five witli the sum of tlie five separate weii^hts proved the accuracy 
of the Avei,:j;hiii<i;. This general method of double weighing was 
followed in ohtahiing all the weights of cheese in the 14 lots. 

The tabulated results show the shrinkage of the different lots and 
the yield of green, paraffined, and cured cheese per hundred pounds 
of milk. In addition to the average results for eacli lot of cheese, 
the individual variations in shrinkage and yield of the single cheeses 
are shown, from which the extent of daily variations from the general 
average figures can be studied l)y anyone interested. 

CJieesc cured at Madison (lot.s lA to 5 A). — Fifty-two ])airs of cheese 
cured at 60° to 70° were weighed one or more times (92 times in all) at 
diil'erent ages, from 21 to 117 days after ])arafnning. In every case 
there was a gain in yield of pasteurized cIuh'sc over raw cheese. The 
gain averaged 4.50 \)0v cent among 10 ))airs of cheese cured 20 to 30 
days, 4.5S per cent among 37 ])airs of cheese cured 30 to 60 days, 
4.38 per cent among 2S pairs of cheese cured 00 to 00 days, and 3.58 
])er cent among 17 ])airs of cheese cured 00 to 117 days. On the 
average of all cases the gain in yield of past(Huized over raw was 
4.22 per cent of the weiglit of th(> cheese. 

Taijh; 2G. — Comparison of yield of raw and paslciirizcd-milk cheese after curing for 
various lemjths of time at Madison, Wis. 







Weisht 


of cured 








Time 


cheese 


per 1(1(1 






Dato 
in.iilp. 


cured 


pounds 


ol uiilk. 






alter 
parallin- 






(!aiu liv 
izal 


[)isteur- 
ioii. 








ing. 


Pasteur- 
ized. 


Raw. 






ion. 


Dai/s. 


roitrida. 


Poll mis. 


Puiinih 


Per cent. 


Apr. 24 


21 


9.27 


S. llli 


0.31 


3. 40 


Mar. 20 


21) 


9. 52 


9. (l(i 


. 40 


5. 08 


21 


2t> 


9. 40 


S. 94 


.40 


5.15 


22 


2ti 


9. 37 


9. 12 


. 25 


2.74 


20 


33 


9. 47 


S. 09 


.48 


5. 34 


17 


32 


9. S7 


9. ('.3 


.24 


2.49 


16 


32 


10.(12 


9. 9l> 


.0(1 


. (10 


15 


32 


9. liS 


9. 3S 


.30 


3. 20 


14 


32 


10. 03 


9. 31 


.09 


7. 3S 


13 


32 


9.72 


,S. NO 


.92 


10.40 


2 


42 


9. 53 


9. 30 


.17 


l.Sl 


7 


42 


9. 57 


9. 49 


.08 


.84 


8 


42 


9.01 


9.51 


. 10 


1.05 


9 


42 


9. 55 


9. 29 


.20 


2.80 


10 


42 


9. t)2 


9.09 


. 53 


5. S3 


-Vpr. 17 


42 


9. 30 


S. 73 


..57 


0. 54 


IS 


42 


9. 13 


8. 04 


.49 


5. 07 


May 1.^. 


44 


9. 43 


S. SO 


.54 


0.07 


17 


44 


9. 15 


S. S5 


.30 


3. 39 


June in 


44 


9. SO 


S. 94 


.92 


10. 29 


Vi 


44 


9. 7(1 


9.311 


.40 


4. 30 


It; 


44 


9. (i4 


9. (14 


.(10 


0. 04 


Feb. 23 


45 


9. 12 


S. 03 


.49 


5.07 


24 


45 


9. 2(i 


S. ;)3 


. 33 


3.09 


27 


45 


9.51 


9. (10 


.51 


5. 07 


2.S 


45 


9. 49 


S. '.19 


. 50 


5. 50 


Mar. 1 


45 


9. 57 


9. OS 


.49 


5. 39 


2 


45 


0.21 


S. 94 


27 


3.02 


Apr. 11 


50 


9. 29 


S. 08 


.31 


3.45 


13 


50 


9. 0(1 


S. SO 


.20 


2.20 


May 10 


50 


S. 95 


8.51 


.44 


5.17 


June 7 


50 


9.19 


8. 79 


.40 


4.55 


9 


50 


9.41 


8. .58 


.83 


9.07 



64 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



Table 26.- 



-Comparison of ijield of raw and pasteurizcd-milk cheese afier curing for 
various lengths of time at Madison, Wis. — Continued. 







Weii,'ht 


of cured 








Time 


cheese 


per lUO 






Date 


cured 

after 

paraffin- 


pounds of milk. 


Gain by jiasteur- 


made. 






izalion. 








ing. 


Pasteur- 
ized. 


Raw. 






1911. 


Days. 


Pounds. 


Pounds. 


Pounds. 


Per cent. 


July 3 


51 


9.06 


8. 38 


0.67 


8.00 


6 


51 


9.35 


9.21 


.14 


1.52 


June 1 


55 


9.59 


9.49 


.10 


1.05 


2 


55 


9 33 


8.95 


. 38 


4.24 


May 29 


55 


9.52 


9. 05 


.47 


5.19 


Apr. 25 


56 


9.62 


9.07 


.55 


6.06- 


May 2 


58 


9. 32 


9.06 


.26 


2.87 


3 


58 


8.82 


8.66 


.16 


1.84 


Apr. 7 


56 


9.36 


8.89 


.47 


5.28 


May 25 


62 


9.19 


8. 86 


..33 


3.72 


22 


62 


9.40 


8.74 


.66 


7. .55 


26 


61 


9.16 


8.80 


. 31; 


4.09 


27 


61 


9 38 


8.9.5 


.47 


5.25 


28 


61 


9.67 


9.35 


.32 


3.42 


19 


66 


9.66 


8.90 


.76 


8.54 


21 


66 


9.16 


8.72 


.44 


5.05 


Apr. 28 


65 


8.97 


8.82 


.15 


1.70 


27 


65 


8.78 


8.10 


.68 


8.40 


24 


65 


9.01 


8.68 


.33 


3. 80 


Mar. 10 


68 


9.10 


8. So 


25 


2 82 


21 


68 


9.15 


8. 67 


.48 


5.53 


20 


68 


9.15 


8.74 


.41 


4.69 


Apr. 17 


72 


9. 03 


8.47 


.56 


6.61 


18 


72 


8.81 


8. 34 


.47 


5.63 


Mar. 17 


74 


9.43 


9.28 


.15 


1.62 


16 


74 


9.72 


9. ,55 


.17 


1.78 


15 


74 


9.34 


9. 06 


.28 


3.09 


14 


74 


9.62 


8.99 


.63 


7.01 


14 


74 


9.37 


8.53 


.84 


9. .84 


Apr. 13 


80 


8.76 


8.58 


.18 


2.09 


11 


80 


8.98 


8.74 


.24 


2.74 


7 


86 


9.09 


8.68 


.41 


4.72 


5 


8() 


9.33 


8.88 


.45 


5.07 


Mar. 9 


84 


9.24 


8.94 


.,30 


3.35 


8 


84 


9.40 


9.09 


.31 


3.41 


7 


84 


9.39 


9.13 


.26 


2.85 


■^ 


84 


9.24 


9.02 


.22 


2.44 


2 


87 


8.93 


8. 64 


.29 


3. 35 


1 


87 


8.97 


8. K5 


.12 


1.35 


Feb. 28 


87 


9.25 


8.71 


.54 


6.20 


27 


87 


9.28 


8.78 


.50 


5.69 


24 


87 


8.98 


8.72 


.26 


2.98 


Mar. 20 


98 


8.94 


8. 62 


.32 


3.71 


21 


98 


8.95 


8.44 


.51 


6.04 


22 


98 


8.91 


8.69 


.22 


2. .53 


17 


104 


9.20 


9. 08 


.12 


1.32 


16 


104 


9.51 


9.35 


.16 


1.71 


15 


104 


9 12 


8.92 


.20 


2.24 


14 


104 


9.41 


8.83 


..58 


6. 57 


13 


104 


9.14 


8.46 


.68 


8. 03 


9 


114 


9.02 


8.72 


.30 


3.44 


8 


114 


9.14 


8.88 


.26 


2.93 


7 


114 


9.14 


8.93 


.21 


2.35 


3 


114 


9.06 


8.8.5 


.21 


2.37 


2 


117 


8.80 


8.51 


.29 


3.41 


1 


117 


8.86 


8.75 


.11 


1.25 


Feb. 28 


117 


9.12 


8.63 


.49 


5.67 


27 


117 


9.15 


8. 69 


.46 


5.29 


24 
Ayerage.. 


117 


8.79 


8.62 


.17 


1.97 




9.289 


8.907 


.38 


4.22 







Cheese stored at New Orleans (lots IB to 4B). — Fifty-four days' 
make represented by 54 raw and 54 pasteurized-milk cheeses were 
shipped to New Orleans in four lots at different times during the 
season. These cheeses showed an increased yield for the new-process 
cheese, as compared with the old, in every case. The average 
figures for each lot are given in Table 27. 



CURING VARIOUS LENGTHS OF TIME. 



65 



Table 27.— Averciffc yield per 100 pound.'? of milk of raw and pasteurizcd-milk cheese 

cured at New Orleans. 





Method. 


Num- 
her of 
days' 
make. 




Yield 


3f cheese 


per 100 pounds of milk. 




Lot 
No. 


(irecn. 


Paraf- 
fined. 


Ship- 
ped 
to New 

Or- 
leans. 


Re- 
ceived 

at New 

Or- 
leans. 


Stored 

one 
month. 


Stored 

two 
months. 


Re- 
ceived 

at 
Madi- 
son. 




(■Pasteurized 


25 
25 


Pounds. 
10.19 
9.67 


Pounds. 
9.69 
9.26 


Pounds. 
9.55 
9.16 


Pounds. 
9.52 
9.14 


Pounds. 
8.85 
8.36 


Pounds. 
8.38 
7.85 


Pounds. 
8.31 

7 78 




Raw 


IB 


Gain, pounds 






.52 
5.37 


.43 
4.64 


.39 
4.25 


.38 
4.16 


.49 
5.86 


.53 
6.75 


53 




Gain, per cent 


■ " 


6 81 




fPasteurized 


9 
9 






9.83 
9.45 


9.40 
9.08 


9. .37 

9.05 


9.26 
8.97 


8.48 
8.12 




8 40 




Raw 


8 01 


2B 


Gain, pounds 






.38 
4 02 


..32 
3.52 


.32 
3.54 


.29 
3.23 


.36 
4.43 




39 




Gain, per cent 




4 87 




fPasteurized 


10 
10 






10.47 
9.93 


9.99 
9.54 


9.92 
9.47 


9.77 
9.34 


9 29 




9 17 




Raw 


8. 69 1 


8 55 


3B 


Gain, pounds. . ... 




.54 
5.44 


.45 
4.72 


.45 
4.75 


.43 
4.60 


.60 ! 

6.90 ...' 


62 




Gain, per cent 




7 25 




f Pasteurized 


10 
10 






10. .38 
9.69 


9.92 
9.31 


9.83 
9.24 


9.78 
9.19 


8.94 




8.71 




Raw 


8.28 




8. 14 


4B 


Gain, pounds 






.69 
7.12 


.61 
6.55 


..59 

6. .38 


.59 
6.42 


.66 
7.97 




.57 




Gain, per cent 




7.00 




Pasteurized 


54 
54 






10.22 
9.68 


9.74 
9.29 


9.64 
9.21 


9.57 
9.16 


8.89 
8.37 




8.56 




Raw 


8.03 


1-4B 


Gain, pounds 




.54 
5. 58 


.45 

4.84 


.43 
4.67 


.41 
4.47 


.52 
6.21 




.53 




Gain, per cent 




6.60 











Amono; the four lots in Table 27, and in the siiminar}' at the 
bottom of the table, it will be seen that the percentage of gain in 
yield of pasteurized cheese over raw fell otT slowly as the green 
cheeses were paraffined and shipped, on the average from 5. 58 to 4.47 
per cent. After these cheeses had been in storage at New Orleans 
for one month, the raw-milk cheeses were found to have slirunk 
more than the pasteurized in the majority of cases, raising the per- 
centage of gain in average yield of pasteurized cheese to 6.21 per 
cent. This was also observed in lot IB after the second month of 
storage, and is confirmed both by the weights taken in New Orleans 
by Mr. Bleecker and by the weights taken at ]\Iadison. It was 
expected that the past euri zed-milk cheese, containing slightly more 
moisture than the raw-milk cheese, would lose more in weight than 
the latter when stored at high temperatures. It was suri)rising to 
find that the reverse is true in most cases. 

The mean daily temperature at New Orleans, as reported by the 
United States Weather Bureau, varied from 71, the average for April, 
to 83, the average for June. It is hkely that the temperature of the 
cheese in the warehouse was somewhat higher than the average 
figures given above, because the warehouse, although well ventilated, 
79994°— Bull. 165"13"^5 



66 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



was necessarily open more or less during the hot days and closed 
durhig the cool nights. 

Cheese cured at New Orleans and at Columbus, Ga. (lots 3G and 
4^).— Forty cheeses, including 20 pasteurized and 20 raw, were 
shipped in two shipments for storage in the South through a firm * 
of cheese dealers in Chicago, who weighed the cheese, both before and 
after storage for one month. 

In the first shipment 1 cheese. No. 243-3, was lost in transit, 
and in the second shipment, 2 cheeses, Nos. 254-1 and 254C1, 
were damaged so that their weights are not included in the following 
summary. In the first shipment, according to the Chicago weights, 
9 pasteurized-milk cheeses weighed 172^ pounds before storage 
and 162^ pounds afterwards. The loss, \Q\ pounds, is 5.94 per cent 
of the original weight. In the same shipment 10 raw-milk cheeses 
w^eighed 189^ pounds before shipment and 175 pounds afterwards. 
The loss here, 14^ pounds, is 7.53 per cent of the original w^eight. 

In the second shijjinent nine pasteurized-milk cheeses weighed 
176| pounds before and 159f pounds after storage. The loss, 16f 
pounds, is 9.49 per cent of the original w^eight of the cheese. In the 
same shipment nine raw-milk cheeses weighed 161 pounds before and 
144f pounds after storage. The loss in this case, 16^ pounds, is 
10.09 per cent of the original weight. In both shipments the raw- 
milk cheese lost a greater per cent of their weight than the pasteurized- 
milk cheese. On comparing the individual cheeses in pairs, it was 
found that in most cases the pasteurized-milk cheese lost less than 
the raw-milk cheese, although in a few cases the reverse was true. 

The weights taken at Madison on the same lots of cheese gave the 
figures shown in Table 28, agreeing substantially with the results 
obtained at Chicago: 

Table 28. — Average yield per hundred pnund/i of milk o/raiv and pasteurized milk cheese 

cured in the South. 





Method. 


Number 

of days' 

make. 


Weight of cheese per 100 pounds of milk. 


Lot 
No. 


Green. 


Paraf- 
fined. 


Shipped 

from 
Madison. 


Received 

at 
Madison. 






9 
10 


Pounds. 
10.47 
9.93 


Pounds. 
9.99 


Pounds. 
9.92 


Pounds. 
9.24 






9.54 


9. 4B 


8. 68 


3C 










.54 
5.44 


.45 
4.72 


.46 
4.86 


.56 






6.44 




Pasteurized 

Raw 


9 
9 




40 


10.38 
9.69 


9.92 
9.31 


9.84 
9.24 


8. S3 
8.24 




.69 
7.12 


.61 
6.55 


.60 
6.49 


.59 




Gain percent 


7.16 









' We arc indebted to Messrs. Crosby & Meyers for their kind cooperation in this work. 



CHEESE CUBED IN WARM ROOM. 



67 



Cheese cured in a warm mom (lots 3D and 4D). — To further test 
the effect of storage at high temperature 40 cheeses, lots 3D and 4D, 
were put for 47 days into a warm curing room at Madison where the 
temperature was hekl at 75° to 85°. 

Table 29.— Average ijicld per hundred pounds of milk of raw mid pasteurized milk cheese 

cured in warm room . 





Method. 


Number 
of days' 
make. 


Wei.^ht of pheese per 100 pounds of milk. 


Lot 

No. 


Green. 


Paraf- 
fined. 


Put in 
warm 
room. 


Taken 
out of 
warm 
room. 




f Pa,<;teuri7-eci 


in 

9 


Poundx. 
10.47 
9.93 


Poundx. 
9.99 
9.54 


Pound.x. 
9.91 
9.46 


Pound.x. 
9. .37 

8.88 




Raw 


3D 


(Jain, pounds 






.54 
5.44 


.45 
4.72 


.45 
4.75 


.49 
5. 52 




Gain, per cent 






f Pasteurized 






9 

10 


10.38 
9.69 


9.92 
9.31 


9.S,i 
9.23 


9. .33 
8.73 




Raw 


4D 


Gain, pounds 






.69 
7.12 


.61 
6.55 


.62 

6.72 


.60 
6.87 




Gain, per cenl 











From these resuhs with eight lots of cheese — IB, 2B, 3B, 4B, 3C, 
41', 3D, and 4D — it can be stated with certainty that pasteurized-milk 
chease does not lose more m weight than raw-milk cheese when stored 
m warm rooms or in the South, after parafTuiing. On the contrary, 
the pasteurized-milk cheese lost on the average a smaller percentage 
of weight in warm storage than the raw-milk cheese. At first this 
fact seemed iiiex])licable, but the reason became clearly apparent from 
inspection of the cheese kept in the warm curing room at Madison. 

Within a few days after going mto the warm room the raw-milk 
cheese became very greasy on the surface, and the grease running on 
to the shelves and the floor marked the spot where each cheese stood. 
The pasteurized-milk cheese, standing alongside of them on the same 
shelves, did not exude grease, or only very slightly in a few cases, and 
the difference between the greasy raw-milk cheese and the dry surface 
of the pasteurized-milk cheese was so marked that there was no 
difiicidty in picking out each kmd by the sense of touch alone. 

To demonstrate further the difference in this respect, each cheese 
of the last lot when put into the warm room was placed on a piece 
of wire gauze in a shallow tin pan, so that the grease running from each 
cheese could be collected. A very little of the paraihn was scraped 
from the surface of each cheese by contact with the wire gauze in the 
bottom of the pan. The total weight of material, practically all 
paraffin, collected from the 1 pasteurized-milk cheeses weighed 0.13 of 
a pound, while the material, mostly fat, with a little paraflin and mold, 
collected from the raw-milk cheeses, weighed 1.92 pounds, which is 
1 .2 per cent of the weight of the raw cheese when placed in the store- 
room. 



68 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



At present we are unable to explain with certainty why the pasteur- 
ized-milk cheese should lose fat less readUy when stored at 70° to 80° 
than the raw-milk cheese. Further study will be made of this ])he- 
nomenon. The purpose of beginning these studies of losses of weight 
in warm rooms was to determme whether the mcreased yield obtamed 
by pasteurization would be offset by increased losses in weight when 
pasteurized-milk cheese are shipped to the South, and it is now fully 
demonstrated that the pasteurized-milk cheese stored in the South 
mamtain their advantage as to increased yield. 

Cheese flaced in cold storage at Waterloo, Wis. (Zoi -5 7i").- -The losses 
of weight observed in 35 pasteurized-milk cheeses put into cold 
storage ^ at 34° at different ages are shown in Table 30. The cheese 
represent seven days' make during July and August, 1911, 

Table 30. — Shrinkage of pasteurized-milk cheese in cold storage. 



Date, 
made. 


Cheese 
No. 


Weight, 
green. 


When 
paraffined. 


When put 
into cold 
storage. 


When taken 

out of cold 

storage. 


Total 


s 


1 
irinkage. 


Age. 


Weight. 


Age. 


Weight. 


Age. 


Weight. 




19n. 




Pounds. 


Days. 


Pounds. 


Days. 


Pounds. 


Days. 


Pounds. 


Pounds. 


Per cent. 


July 19 


264-1 


20.60 


9 


19.60 


m 


(') 


100 


18. 15 


2.45 


11.89 


19 


264-2 


21.11 


1 


20.70 


1 


20.70 


100 


20. 38 


.73 


3.45 


19 


264-3 


20.10 


7 


19.21 


7 


19.21 


100 


19.15 


.95 


4.72 


19 


264-4 


21.07 


9 


20.05 


14 


20.04 


100 


19.85 


1.22 


5.79 


19 


264-5 


19.89 


9 


18.90 


28 


18.70 


100 


18.28 


1.61 


8.09 


19 


264-6 


20. 45 


9 


19.44 


41 


18. 95 


100 


18. 65 


1.80 


8.80 


21 


265-1 


22.49 


8 


21.60 


(2) 


(') 


99 


20.10 


2.39 


10.62 


21 


265-2 


17.98 


1 


17.58 


1 


17.58 


99 


17. 45 


..53 


2.94 


21 


265-3 


20.21 


7 


19.35 


7 


19.35 


99 


19.25 


.96 


4.75 


21 


265-4 


18.86 


S 


17.98 


14 


17.92 


99 


17.75 


1.11 


5.89 


21 


265-5 


19.58 


8 


18.68 


28 


18.42 


99 


18. 05 


1..53 


7.81 


21 


265-6 


19.25 


8 


18.40 


28 


18. 13 


99 


17.68 


1.57 


8.16 


21 


265-7 


19.75 


8 


18.86 


40 


18.36 


99 


18.10 


1.65 


8.35 


25 


267-1 


20. 82 


11 


19.86 


(2) 


C') 


95 


18.50 


2.32 


11.14 


25 


267-2 


20.29 


1 


19.95 


1 


19.95 


95 


19.80 


.49 


2.41 


25 


267-3 


19.97 


7 


19.11 


7 


19.11 


95 


18.90 


1.07 


5.35 


25 


267-4 


21.55 


11 


20.58 


14 


20. 58 


95 


20.38 


1.17 


5.43 


25 


267-5 


20.23 


11 


19.25 


29 


18.98 


95 


18. 58 


1.65 


8.15 


25 


267-6 


22.20 


11 


21.31 


43 


20. 62 


95 


20.25 


1.95 


8.78 


27 


269-1 


18.70 


9 


17.80 


(2) 


{■") 


93 


16.45 


2.25 


12.03 


27 


269-2 


19.88 


1 


19.45 


1 


19.45 


93 


19.20 


.68 


3.42 


27 


269-3 


19.85 


7 


19.01 


7 


19.01 


93 


18.95 


.90 


4.53 


27 


269-4 


20.87 


9 


19.92 


14 


19.92 


93 


19.55 


1.32 


6.32 


27 


269-5 


IS. 80 


9 


17.91 


27 


17.60 


93 


17.22 


l.,58 


8.40 


27 


269-6 


20.22 


9 


19.22 


41 


18.61 


93 


18.25 


1.97 


9.74 


Aug. 1 


272-1 


21.91 


11 


20. 65 


m 


(2) 


89 


19.00 


2.91 


13.28 


1 


272-2 


19.78 


1 


19.30 


1 


19.30 


89 


19.05 


.73 


3.69 


1 


272-3 


19. 40 


7 


18.55 


7 


18. 55 


89 


18.22 


1.18 


6.08 


1 


272-4 


21.82 


11 


20.55 


14 


20.55 


89 


20.25 


1.57 


7.19 


1 


27^5 


21.80 


11 


20.57 


29 


20. 20 


89 


19.90 


1.90 


8.71 


1 


272-6 


21.75 


11 


20.50- 


46 


19.75 


89 


19.50 


2.25 


10.34 


1 


276-1 


19.90 


11 


18.63 


(2) 


(') 


81 


17.20 


2.70 


13.66 


8 


276-2 


20.42 


1 


19.98 


1 


19. 98 


81 


19.60 


.82 


4.01 


8 


276-3 


20.44 


7 


19.50 


7 


19. .50 


81 


19.30 


1.14 


5.57 


8 


276-4 


19.90 


11 


18.66 


15 


18. 63 


81 


18.40 


1..50 


7. .53 


8 


276-5 


19.70 


11 


18. 45 


28 


18.21 


81 


17.75 


1.95 


9.89 


22 
22 


283-1 
283-2 


20.10 
19.90 






1 


19.50 


67 
67 


18.10 
19.38 


2.00 
.52 


9.95 

2.61 


i' 


"ig.'so' 


22 


283-3 


19.68 


8 


18.81 


8 


18.81 


67 


18.75 


.93 


4.72 


22 


283-4 


18.80 


11 


17.90 


15 


17.70 


67 


17.40 


1.40 


7.44 


22 


283-5 


19.84 


11 


18.84 


29 


18.62 


67 


18.45 


1.39 


7.00 


22 


283-6 


18.65 


11 


17.62 


42 


(') 


67 


16.80 


1.85 


9.92 


.SUMM.'lRY. 


No. ofch 
Age whei 
Average 


Bese 




1 


7 
day. 


1 


7 
week. 


2 weeks. 


4 we 


7 
eks. 


6 w 


6 
eeks. 


7 
In cellar. 


1 stored. 




total 


shrinkage, 






















per cen 


t 






3.22 




5.10 


6.51 




8.29 




9.29 


11.78 












1 



1 In warehouse at Waterloo, Wis., by courtesy of the Roach & Seeber Co. 



2 Cured in cellar. 



CAUSES OF INCREASED YIELD. 69 

Altliough the seven cheeses put into storage at the age of 1 flay 
showed an average of only 3.22 per cent shrinkage after three months, 
yet they were not well hroken down and required further curing at 
60° to 70° to get rid of their curdy, lumpy texture. The cheese 
I)araflincd and stored when 1 week old showed an average total 
shrinkage of 5.10 per cent, and these were found to be thoroughly 
broken down when taken out of cold storage. This series appears 
to indicate that the quality of pasteurized-milk cheese is not damaged 
by placing in cold storage at the age of 1 week, while the shrinkage 
(5.10 per cent) is about half that of the duplicate cheese, cured in 
the cellar at Madison (11.78 per cent), as shown at the bottom of 
the table. 

THE CAUSES OF THE INCREASED YIELD FROM PASTEURIZED MILK. 

THE LOSSES OF FAT FROM VAT AND PRESS. 

The increased yield of green cheese from pasteurized milk, amount- 
ing to over 5 ])er cent (Table 20), is due partly to the fact that about 
half of th(^ fat lost in the whey and drippings by the old pi'ocess is 
retained in the cheese by the new process of making. Also it is 
found that a little more moisture can safely be incorporated in the 
new-process cheese without danger of spoiling it, but on the contrary 
giving it a moist, fat a])pearance wliich consumers generally like. 
The loss of fat in the whey is caused j)artly by the passage of the 
cui'd kiiiv(>s through the curd in cutting, at which time a considerable 
})i-oj)ortion of fat is brushed away from the surface of the curd cubes. 
J)iu-ing the stirring and heating some further fat globules are lost 
from the ciu'd cubes, and still further losses occur after milling and 
during ])ressing. In the new j)rocess of making cheese from pasteur- 
ized milk the curd is so (irm and elastic (not brittle) at the time of 
cutting that the loss of fat in the whey averages only about one-half 
that observed in cheese making b}^ the ordinary process. 

The average fat content of whey from good clean milk is stated to 
be 0.30 per cent and from average cheese factory milk 0.36 per cent.* 
On a great many days during the past two and one-half years the 
milk supply in the receiving vat has been divided and one half made 
up by the regular methods and the other half by the new method. 
The quality and composition of the milk was thus the same in both 
vats. On the 24 days listed in Table 31 the average fat content of 
the whey from the i-egular vats was 0.25 per cent and from the 
pasteurized-milk vats was 0.159 per cent. 

» Van Slyke and Publow, loc. cit., pp. 1S9, 190. 



70 



CHEDDAE CHEESE FROM PASTEUEIZED MILK. 



Table 31. — Comparison of the percentage of fat in whey by new method and by regular 

method of cheese making. 



Date. 


Fat in 
milk. 


New method. 


Regular 


method. 


Weight 
of milk 
used. 


Fat in 
whey 
when 
drawn. 


Weight 
of milk 
used. 


Fat in 
whey 
when 
drawn. 


1911. 


Per ct. 


Pounds. 


Per cent. 


Pounds. 


Per cent. 


Aug. 29 


4.1 


294A 


0.14 


290 


0,17 


30 


3.6 


344' 


.14 


344 


.26 


Sept. 1 




322 


.15 


320 


.20 


5 


"'4.'6" 


29U 


.17 


292 


.28 


6 


3.6 


276 


.19 


276 


.32 


7 


4.1 


286^ 


.18 


286i 


.32 


8 




292 


.16 


795 


.26 


1909. 












July 21 


4.0 


200 


.15 


200 


.21 


22 


3.9 


200 


.12 


200 


.20 


23 


4.0 


20(J 


.15 


200 


.19 


24 


4.0 


200 


.12 


200 


.22 


Aug. 12 


3.7 


200 


.16 


200 


.26 


1908. 












July 18 


4.1 


200 


.12 


200 


.22 


Oct. 1 


4.7 


200 


.20 


200 


.30 


2 


4.5 


200 


.18 


200 


.29 


7 


4.4 


200 


.14 


200 


.19 


8 


4.0 


200 


.15 


200 


.25 


Sept. 1 


4.3 


200 


.17 


200 


.32 


2 


4.2 


200 


.18 


200 . 


.30 


14 


4.2 


200 


.18 


200 


.24 


16 


4.0 


200 


.13 


200 


.27 


17 


4.4 


200 


.19 


200 


.29 


IS 


4.4 


200 


.18 


200 


.25 


19 
A verage . . 


4.2 


200 


.17 


200 


.23 






.159 




.25 











In these cases the small amount of milk handled in each vat per- 
mitted hand stirring, and neither the rake nor the agitator was used. 
By tliis means the w^hey fat of the regular-process vats was kept at a 
lower figure, perhaps, than could have been done with large vats, 
as handled in a commercial factory using the regular process. 

On 22 days, using 1,200 to 2,000 pounds of pasteurized milk in 
each vat, the percentage of fat in the whey at the time of drawing 
the whey averaged 0.17 per cent, as shown in the following table. 
In these cases the vats were stirred with an agitator. 



Table 32. — Fat content of ivhey from pasteurized-milk cheese. 



Date. 


Fat in 

whey two 

hours after 

cutting. 


Weight 
of mUk 
handled. 


Weight 
of cheese. 


1910. 


Per cent. 


Pounds. 


Pounds. 


May 25 


0.14 


1,234 


139 


26 


.16 


1,322 


153 


27 


.18 


1,337 


144 


June 1 


.17 


1.578 


166 





.12 


2,061 


226 


7 


.15 


1,427 


159 


8 


.14 


1,431 


158 


9 


.18 


1,360 


147 


10 


.17 


1,448 


162 



CAUSES OF INCREASED YIELD. 71 

Table 32. — Fat content of wlmj from pant e.iirized- milk cheese — OouLiuued. 



Date. 


Fat in 

whey two 

h .ur.-i alter 

cutting. 


Weight 
of milk 
handleti. 


Weight 
of c-hee.se. 


1910. 
Juno 14 
10 
17 
211 
21 
22 

24 

■IS 

2y 

30 

July r, 
() 

Average.. 


PcT cent. 
0.21) 
.20 . 
.20 
.20 
. 23 
.14 
.10 
.IS 
.24 
. 14 
.17 
. US 
.14 


Pounds. 
l.:i!)s 
1,10.") 
1,320 

1 , ,")SS 
1 , 202 
1,347 
1 . 320 
1 , 337 
1,277 
1,210 
1,243 
1,242 
1,229 


Pounds. 
148 
120 
152 
170 
144 
144 
139 
139 
130 
130 
131 
125 
134 


.17 











Most of tlio loss of fat from curd occurs at the moment of eutting, 
as shown by the tio;ur(>s in Table 33. On 23 (hiys samples of whey 
were taken chiily from the vat as soon after cutting as it was possible 
to obtain any clear whey that is, in four to six minutes. The fat 
content of this whey, sami)le(l five minutes after cutting, tested 0.47 
per cent on tlie average of 23 days, Avhile the average test of samples 
taken from the sanu' vats two hours after cutting was 0.16 {)(>r cent. 
The average weight of milk handled (hiily in the vat was 1,110 
pounds, and the average fat test of the milk was 4 per cent. 

Table 315. — Fat content of wliey at time ofcutti>i<i curd and J hours later. 





'I'inie all 


^r c'ult.ng 








curd. 






Date. 






Weight 
of milk- 
handled. 


Weight 
of cheese. 


4 to 6 


9 




minutes. 


hours. 






1910. 


%/at- 


%/"t. 


Pounds. 


Pounds. 


.Xjir. s 


0. 45 


0. 10 


1,011 


102 


12 


.4f> 


. 1',) 


1,011 


104 


13 


.40 


.15 


907 


98 


14 


.40 


. 14 


1,045 


lOS 


15 


.50 


.12 


1,001 


100 


IS 


.35 


.13 


993 


103 


19 


. 55 


. 22 


900 


97 


22 


.40 


.10 


lO,) 


77 


25 


.42 


. 19 


1 , 005 


117 


20 


. 52 


.17 


940 


103 


27 


..52 


. 10 


1,004 


109 


28 


. 57 


.15 


972 


102 


29 


.4.', 


. 14 


790) 


102 


May 3 


. 05 


. 10 


1 , 04 1 


122 


4 


.07 


. n; 


1,0.55 


118 






. 17 


1,119 


129 





. 50 


.20 


917 


97 


10 


52 


. 10 


1 , 2SS 


141 


11 


. .50 


. 15 


1,285 


138 


is 


, 35 


.15 


1 , 239 


137 


19 


.40 


. 14 


1,180 


130 


23 


.25 


. 12 


2, 477 


208 


24 
Average.. 


.45 


.19 


1,454 


154 


.47 


.16 


1,110 


119.8 



72 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

The reason for the decrease in percentage of fat in whey at two 
hours after cutting is tliat there was httle fat lost from the curd 
during the time the whey was being expelled, so that the fat lost 
from the curd cubes at the moment of cutting was diluted about 0.47 
divided by 0.16 = 3 times by the water expelled from the curd during 
the two-hour period. 

Losses of fat after drawing the whey. — On several days the whey 
drippings from the pasteurized-milk curd, from the time the curd 
was all on the rack up to the time when it was taken from the press, 
were collected, weighed, and tested for fat. From this could be cal- 
culated the weight of fat lost in the drippings, as shown in Tables 34, 
35, and 36: 

Table 3i.- Loss of fat in drippings in 2 hours <ind 50 miniUes — From dipping to 
hooping —Pusteurized-niilk curd. 



Date. 


Total 
weight of 
drippings 
collected. 


Fat in drippings. 


Weight 

of cheese 

made. 


1910. 
Apr. 12 
13 
14 
15 
18 
19 
20 
21 
22 
25 

ToUil 


Pounds. 
29 
28 
31 
33 
21 
26 
20 
25 
21 
24 


Per cent. 
0.27 
.27 
.30 
.25 
.20 
.10 
.15 
.18 
. 12 
.20 


Pound. 
0.078 
. 075 
.093 
.082 
.042 
.020 
.030 
.045 
.025 
.048 


Pounds. 
104 
98 
108 
100 
103 
97 
91J 
95i 
77' 
117 


258 




.544 


991 





Table 35. — Losses of fat in drippings before pressing pasteurized-milk curds. 





Drippings in IJ hours — dip- 


Drippings in IJ hours— mill- 




Date. 


ping to milling. 


ing to hooping. 


Weight 
















Weight. 


Fat content. 


Weight. 


Fat content. 




1910. 


Pounds. 


Per cent- 


Pound. 


Pounds. 


Per cent. 


Pound. 


Pounds. 


Apr. 27 


35 


0.02 


0.007 


5.0 


1.8 


0. 090 


109 


28 


24 


.05 


.012 


5. 


1.8 


.0!)ll 


102 


29 


24 


.02 


.050 


3.0 


1.8 


.054 


84 


May 3 


25 


.08 


.020 


2.5 


1.8 


. 045 


122.\ 


4 


25 


.05 


.012 


1.5 


.6 


.009 


118 


5 


29 


.07 


.020 


3.0 


1.7 


.051 


129 


10 


20 


.07 


.018 


4.0 


1.2 


.048 


141 


11 


24 


.07 


.017 


3.0 


1.6 


.048 


137i 


13 


25 


.16 


. 040 


3.0 


2.0 


.060 


103 


18 


24 


.06 


.014 


4.5 


2.0 


. 090 


137 


19 


25 


.05 


.012 


5.0 


1.4 


. 070 


125 


23 


.38 


.04 


.015 


9.0 


1.5 


. 135 


268 


24 

Tolal 

(" a 1 r 11 - 
laledfor 


2ti 


.14 


.036 


5.0 


2.0 


. 100 


162 


350 




.273 


53. 5 




. 890 


1,738 






IKlbs.of 
















cheese. . . 


2.01 




.00157 


.3078 




.00512 











CAUSES OF INCREASED YIELD. 73 

Table 36. — Loss of fat in drippings from pasteurized- milk cheese in press. 



Date. 


Total 
weight 
of cheese 
pressed. 


Total 
weight of 
drii)i)iiigs. 


Fat in drippings. 


1910. 
May 10-20 
2;i-27 

'I'otcil 

(-' U 1 (• 11 - 

lilted for 
KMIjs. ot 
clieesfc . . 


Pounds. 

808 
873 


Pounds. 
24 
32 


Per cent. 
3.85 
3.2 


Pounds. 
0.92 
1.02 


1,081 


50 
.33 




1.94 
.0115 











Summary of losses of fat by the new method of cheese making. — The 
total loss ol" fat froju cheese in tli(> new process is about 1.6 per cent 
of the weifrht of the cheese, as sliovvn in the following sumjnary of 
the ])rec(>(ling tables : 

'J'Aiii.K 'M. —Total losses of fat in making W pounds of cheese from pasteurized milk. 



Whey when drawn 

Drippings from curd before inilhng. . . . 
Drippings from curd in vat after miUin; 
Drippings from press 

Total 



Total, 
weiglit. 


Fat content. 


Pounds. 


Per cent. 


Pound. 


87.4 


0. It; 


0. 1400 


2.01 


.08 


.0010 


.31 


1.00 


.0051 


.33 


3.40 


.115 


90. 05 




.1583 





Lo.ss of 
fat from 
cheese. 



Per cell!. 
1.400 
.OJii 
.051 



1.58o 



The average total loss of fat from 100 pouiuls of milk handled by 
the new process of clieese making is seen to be on the average 0.158 
l)oiinds of fat, or a little less than 4 })er cent of the total fat content 
of milk containing 4 per cent fat. The loss of fat from 100 j)oiinds 
of milk in ordinary cJieese making under average factory coiulitions 
has been found to amount to 0..38 of a ])ound of fat, or 0.36 per cent 
of fat in the whey, or 9 ])er cent of the total fat content of the milk.' 

It wdll be seen from these figures that the loss of fat is reduced to 
less than one-half by the new process of cheese making. It might 
be expected from tliis statement that each day's make of pasteurized- 
milk cheese tested by the Babcock test would show a higher percentage 
of fat than the sani(> day's raw-milk cheese. In Table 38, however, 
it is seen that in 15 cases out of 21 the pasteurized-milk cheese tested 
lower in fat (0.65 per cent lower on the average) than the raw-milk 
cheese. 

THE INCREASED MOISTURE CONTENT OF PASTEURIZED-MILK CHEESE. 

Tliis is due to the fact that there is an increased content of moisture 
as well as of fat in the new-])rocess cheese, and in most cases the in- 
crease of moisture is m-eater than the increase of fat. On this 



Van Slyke and Publow, loc. eit., p. 189. 



CHEDDAE CHEESE FROM PASTEURIZED MILK. 



account the moisture content of pasteurized cheese listed in the 
table below is greater than that of the raw-milk cheese in 29 cases 
out of 33, and the average percentage was 1.68 greater. 

The cheeses listed in the table were the same as those in Table 26, 
and the testing for fat and moisture was done immediately after the 
last weights had been taken for the determination of yield and 
shruikage. The samples of cheese weighed into the Babcock test 
bottles were rapidly dissolved in a mixture of hot water and sul- 
phuric acid, as suggested by one of us in a previous paper.' 

Table 38. — Comparison of the fat and moisture content of raw and pasteurized milk 

cheese cured at Madison. 



Date. 


Moisture content of cheese. 


Fat content of cheese. 


Pasteur- 
ized. 


Kaw. 


Ditt'erence. 


Pasteur- 
ized. 


Raw. 


Dilference. 


1911. 

Feb. 24 

27 

28 

Mar. 1 

•> 

3 

8 

9 

10 

13 

14 

15 

Ui 

17 

20 

21 

22 

Apr. 5 

7 

11 

13 

17 

18 

24 

27 

28 

May 2 

3 

8 

10 

15 

17 

Average. . 


Per ct. 
30.50 
33.55 
32.52 
32. 55 
31.00 
31.05 
31.90 
32. 37 
32. 77 

32. 45 

33. 15 
33.51 
31.02 

33. 40 

34. 15 
32. 72 
32.90 
34. 00 
34.10 
34. 52 
32.90 
31.78 
33.47 
33.55 
32.28 
31.80 
34.17 
32.03 
31.02 

32. 87 
31.05 

33. 47 
31.87 


Per ct. 
30. 15 
30.15 
30.05 
31.25 
30.75 
31.47 
29.75 
30. 17 
31.32 
31.45 
30.00 
31.95 
30.90 
30. S7 
33. 22 
31.58 
30.10 
32.20 
32. 25 
31.92 
31.97 
30.17 
31. 55 
30.15 
32. 68 
32.70 
33.22 
31.25 
30.87 
31.05 
30. 45 
32.25 
32.58 


+ Perct. 
0.35 
3.40 
2.47 
1.30 
.85 


-Per ct. 


Per ct. 
38.86 


Per ct. 
39.10 


—Perct. 
0.24 


+ Per ct. 




































0.42 










2.15 
2.20 
1.45 
1.00 
3. 15 
1.56 

.72 
2.53 

.93 
1.14 
2.80 
1.80 
1.85 
2. 00 

.93 
1.01 
1.92 
3.40 


37.44 
37.99 
38.01 


38. 10 
38.16 
38.04 


. 72 
!l7 










57 




























38. 28 
38.01 
38.01 


38.36 
38. 39 
37.97 


.08 






!o4 
































36.93 
36. 56 


37.09 
36.85 


. 16 
.29 












36.84 
36.81 
38.22 
39.18 
38.64 
37.93 
39. 55 
40.68 
37. 97 
39.28 
37.97 
38.10 


37. 02 
37.94 
39.95 
38.86 
38.66 
39. 08 
40.68 
41.43 
39. 06 
39.27 

38. 06 
37.67 


. 18 
1.13 
1.73 












.40 
.90 


.32 




.02 
1. 15 
1.13 

.75 
1.09 


.95 
1.38 

.15 
1.82 
1.20 
1.22 


















.01 




.69 


.71 


.43 






32. 69 


31.28 


1.68 


.61 


38.21 


38.59 


.65 


.26 



The combined effect upon the percentage composition of cheese 
caused by increasing both the fat and moisture content is shown in 
the following example : 

Ten pounds of raw-milk cheese of the same average percentage 
composition as in Table 38, as shown at I, below, would contain the 
weights of fat, moisture, and casein, etc., shown at II. If by pas- 
teurization the fat content of the cheese is increased about 4 })er cent 
of itself, and the moisture content is increased about 12^ per cent of 
itself, there will be obtained 10.54 pounds of pasteurized-milk cheese 



1 Sammis, J. L. The determination of fat in cheese by the Babcock test. 
Engineering Chemistry, vol. 1, no. 8, p. 604. Easton, Pa., -Vug., 1909. 



Journal of Industrial and 



QUALITY OF PASTEURIZED-MILK CHEESE. 75 

as shown at III instead of 10 pounds of raw-milk cheese, a theoretical 
gain of 5.4 per cent in the >-ield of cheese. (The actual gani shown 
in Table 20 was 5.37 per cent.) The percentage composition of this 
])asteurized cheese will be as shown at IV, which agi'ees closely with 
tlie average conij)()sition of tJie pasteurized-milk cheese shown at the 
bottom of Table 38. 

I- 11. III. IV. 

Fat 38.59 per cent. 3.859 pounds+0. 154 pounds=4.013 pounda. 38.07 per cent- 

MuLsture. . 31.28 per cent. 3.128 pounds f 0.391 pounds=3.519 pounds. 33.37 per cent. 

Casein, etc. 30.13 per cent. 3.013 pounds-)- .... pouuds=3.013 pounds. 28.57 per cent. 

100.00 per cent. 10.000 pounds. 10.545 pounds. 100.00 per cent. 

The increased moisture content of pasteurized-milk cheese made 
by this process is due to the effect of pasteui'ization on the properties 
of curd, as stated on page 25. 

THE QUALITY OF PASTEURIZED-MILK CHEESE, 

SCORES AND CRITICISMS OP I'A.STEURIZED AND R.VW MILK CHEESE. 

The milk supply u.sed at Madison is no better than the average 
cheese-factory milk. Sunday's milk is delivered on Monday tlu-ough- 
out the year and is therefore inferior to that of the other days. Cheese 
from every day's make dining the season was scored by two judges, 
Mr. U. S. Bacr, assistant dairy and food commissioner of the State of 
Wisconsin, and Mr. A. T. Bruhn, junior dairyman. United States 
De})artinent of Agriculture, who during the past year have scored the 
cheese sent to the monthly scoring exhibition, conducted by the 
Wisconsin Experiment Station. The judges worked independently 
and pinned their scor(vsheets to each cheese without knowing even the 
immbers of the cheese, which were turned toward the wall. Their 
scores show close agreement with each other in most cases and leave 
no doubt as to the relative quality of the cheese scored. After 
linishing about 20 of the cheeses, they turned them around and added 
the cheese numbers to the sheets. In general, a score of 92 or above 
indicates that the cheese is of good quality and salable at full market 
]jrice. A cheese scored l)ek)W 92 is likely to be cut in price in a dull 
market. Tallies 39 to 46 show the .scores of both judges as well as 
the average scones, which latter are used in the discu.ssion. Raw-milk 
cheese is in all (lases indicated by the letter C attached to the serial 
number. 

CHEESE CURED AT MADISON AT NORMAL TEMPER.\TURB. 

Lots lA, 2A, SA, and 4^.— These lots include 53 pairs of cheese 
cured in the cellar at Madison. The temperature of the curing room 
showed daily about 3° to 5° ditference between maxmuim and mini- 
mum and ranged from 60° to 73° from February to July, 1911. By 
opening the windows at night only, it was kept at 60" to 70" from 
July to October. 



76 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



The scores of the 53 pairs of cheese are as shown in Table 39. 
The average score of all the pasteurized-milk cheese is 92.75 and of 
the raw-milk cheese 89.09. 

Table 39. — iScores of 53 pairs of raw and pasteurized cheese {lots lA, 2 A, SA, and 4A) 

cured at Madison. 

LOTS lA AND 2A, SCORED JULY 17, IQU. 



Tem- 






Scored 


by U. S. Baer. 


Scored 


by A. T. 


Bruhn. 




Average 




pera- 
ture of 


Date 


Cheese 






































curing 
room 
sa. m. 


made. 


No.i 


Fla- 
vor. 


Tex- 
ture. 


Total. 


Flavor. 


Tex- 
ture. 


Total. 


Flavor. 


Tex- 
ture. 


Total. 


°F. 


1911. 
























Feb. 24 


172 


41.0 


26.0 


92.0 


40.0 


20.5 


91.5 


40.50 


20.25 


91.75 




24 


1720 


37.0 


27.0 


89.0 


38.0 


27.0 


90.0 


37.50 


27.00 


89.50 




27 


173 


43.0 


28.5 


96.5 


42.5 


28.0 


95.5 


42.75 


28.25 


96.00 




27 


173C 


38.0 


27.0 


90.0 


40.0 


27.0 


92.0 


39.00 


27.00 


91.00 




28 


174 


41.0 


27.0 


93.0 


41.0 


27.5 


93.5 


41.00 


27.25 


93.25 




28 


1740 


39.0 


26.0 


90.0 


39.0 


26.5 


90.5 


39.00 


26.25 


90.25 




Mar. 1 


175 


41.0 


27.0 


93.0 


40.0 


26.0 


91.0 


40.50 


20.50 


92.00 




1 


1750 


40.0 


26.0 


91.0 


40.0 


26.5 


91.5 


40.00 


20.25 


91.25 




2 


170 


40.0 


28.0 


93.0 


41.0 


27.0 


93.0 


40.50 


27.50 


93.00 




2 


17C0 


37.0 


27.0 


89.0 


39.0 


27.0 


91.0 


38.00 


27.00 


90.00 




3 


177 


40.0 


27.0 


92.0 


40.0 


26.5 


91.5 


40.00 


26.75 


91.75 




3 


1770 


38.0 


26.0 


89.0 


38.0 


26.0 


89.0 


38.00 


26.00 


89.00 




7 


178 


40.0 


26.0 


91.0 


40.0 


27.0 


92.0 


40.00 


26.50 


91.50 




( 


1780 


38.0 


27.0 


90.0 


39.0 


27.0 


91.0 


38.50 


27.00 


90.50 




8 


179 


40.0 


27.0 


92.0 


41.0 


27.5 


93.5 


40.50 


27.25 


92.75 




8 


1790 


35.0 


26.0 


86.0 


38.0 


26.0 


89.0 


36.50 


26.00 


87.50 




9 


180 


41.0 


26.0 


92.0 


41.0 


27.0 


93.0 


41.00 


26.50 


92.50 




9 


ISOO 


39.0 


26.0 


90.0 


40.5 


26.5 


92.0 


39.75 


26.25 


91.00 




11) 


181 


41.0 


26.0 


92.0 


42.0 


27.0 


94.0 


41.50 


26. 50 


93.00 




10 


1810 


38.0 


27.0 


90.0 


39.0 


20.5 


90.5 


38.50 


26.75 


90.25 




13 


182 


40.0 


27.0 


92. 


41.0 


27.0 


93.0 


40.50 


27.00 


92.50 




13 


182(; 


41.0 


26.0 


92.0 


40.0 


27.0 


92.0 


40.50 


26. 50 


92.00 




14 


183 


40.0 


26.0 


91.0 


40.0 


26.5 


91.5 


40.00 


26. 25 


91.25 




14 


1830 


40.0 


27.0 


92.0 


40.0 


26.5 


91.5 


40.00 


26. 75 


91.75 




15 


184 


40.0 


26.0 


91.0 


41.0 


27.0 


93.0 


40.50 


26.50 


92.00 




15 


1S40 


40.0 


27.0 


92.0 


41.5 


27.0 


93.5 


40. 75 


27.00 


92.75 


(iO 


10 


1S5 


40.0 


26.0 


91.0 


41.5 


27.0 


93.5 


40.75 


26.50 


92. 25 




10 


1S50 


35.0 


26.0 


86.0 


41.0 


27.0 


93.0 


38.00 


26.50 


89.50 


02 


17 


180 


42.0 


28.0 


95.0 


41.0 


26.5 


92.5 


41.50 


27.25 


93. 75 




17 


ISOO 


41.0 


28.0 


94.0 


41.0 


27.0 


93.0 


41.00 


27.50 


93.50 


03 


20 


187 


43.0 


27.0 


95.0 


41.0 


26.0 


92.0 


42.00 


26.50 


93.50 




20 


1870 


35.0 


25.0 


85.0 


39.0 


26.5 


90.5 


37.00 


25.75 


87.75 


00 


21 


188 


43.0 


28.0 


96.0 


41.0 


27.0 


93.0 


42.00 


27.50 


94. 50 




21 


1880 


38.0 


26.0 


89.0 


40.0 


27.0 


92.0 


39. 00 


26.50 


90.50 


00 


22 


189 


43.0 


27.0 


95.0 


42.0 


28.0 


95.0 


42.50 


27.50 


95.00 




99 


1890 


39.0 


27.0 


91.0 


40.0 


27.0 


92.0 


39.50 


27.00 


91.50 


02 


Apr. 5 


198 


43.0 


27.0 


95.0 


42.0 


28.0 


95.0 


42.50 


27.50 


95.00 




5 


1980 


41.0 


27.0 


93.0 


41.5 


28.0 


94.5 


41.25 


27.50 


93. 75 




7 


200 


42.0 


27.0 


94.0 


42.0 


27.0 


94.0 


42.00 


27.00 


94.00 


04 


7 


200O 


35.0 


25.0 


.8.5.0 


40.0 


20.0 


91.0 


37.50 


25. 50 


88.00 




11 


202 


42.0 


26.0 


93.0 


42.5 


27.0 


94.5 


42.25 


26. 50 


93.75 




11 


2020 


39.0 


26.0 


90.0 


40.0 


27.0 


92.0 


39.50 


26. 50 


91.00 




13 


204 


41.0 


27.0 


93.0 


42.0 


28.0 


95.0 


41.50 


27.50 


94.00 




13 


204O 


39.0 


26.0 


90.0 


40.0 


27.0 


92.0 


39.50 


26. 50 


91.00 




17 


200 


41.0 


27.0 


93.0 


41.0 


27.0 


93.0 


41.00 


27.00 


93.00 




17 


200O 


40.0 


25.0 


90.0 


38.0 


25.0 


87.0 


39.00 


25.00 


88.50 




IS 


207 


43.0 


20. 


94.0 


41.5 


27.0 


93.5 


42. 25 


20. .50 


93.75 




IS 


207O 


42.0 


25.0 


92.0 


40.0 


25.0 


90.0 


41.00 


25.00 


91.00 




24 


211 


43.0 


20.0 


94.0 


42.0 


27.0 


94.0 


42.50 


26. 50 


94.00 




24 


2110 


.39.0 


25.0 


89.0 


39.0 


27.0 


91.0 


39.00 


26.00 


90.00 




27 


214 


40.0 


25.0 


90.0 


42.5 


27.0 


94.5 


41.25 


20. 00 


92. 25 




27 


2140 


37.0 


24.0 


86.0 


37.0 


26.0 


88.0 


37.00 


25.00 


87.00 




28 


215 


42.0 


27.0 


94.0 


42.0 


27.0 


94.0 


42.00 


27.00 


94.00 


(iO 


28 


2150 


37.0 


25.0 


87.0 


38.0 


26.0 


89.0 


37.50 


25.50 


88. 00 




May 2 


210 


41.0 


20,0 


92.0 


40.5 


26.0 


91.5 


40.75 


26. 00 


91.75 


AS 


9 


210O 


37.0 


25.0 


87.0 


.38. 


26.0 


89.0 


37.50 


25.50 


88.00 




3 


217 


42.0 


28.0 


95.0 


41.5 


27.0 


93.5 


41.75 


27.50 


94.25 


(;2 


3 


2170 


37.0 


25.0 


87.0 


40.0 


26.0 


91.0 


38.50 


25.50 


.89. 00 




S 


220 


41.0 


27.0 


93.0 


42.0 


27.0 


94.0 


41.50 


27. 00 


93. 50 


02 


s 


2200 


34.0 


25.0 


84.0 


39.0 


25.0 


89.0 


30. 50 


25.00 


86.50 




10 


222 


40.0 


25.0 


90.0 


40.0 


27.0 


92.0 


40.00 


26.00 


91.00 


03 


10 


2220 


37.0 


25.0 


87.0 


40.0 


20.0 


91.0 


38.50 


25.50 


89.00 




1.1 


225 


40.0 


20.0 


91.0 


42.0 


28.0 


95.0 


41.00 


27.00 


93. 00 


04 


15 


2250 


38.0 


26.0 


89.0 


39.0 


27.0 


91.0 


38. 50 


20. 50 


90.00 




17 


227 


41.0 


20.0 


92.0 


41.0 


27.0 


93.0 


41.00 


26. 50 


92. 50 


07 


17 


2270 


35.0 


24.0 


84.0 


37.0 


25.0 


87.0 


36.00 


24.50 


85.50 



'C" in this column indicates raw-milk cheese. 



QUALITY OF PASTEURIZED-MILK CHEESE. 



77 



Table 39.— Scores of 53 pairs of raw and pasteurized cheese (lots lA, 2 A. 3 A. and 4 A) 
cured at Madison — Continued. 

LOT 3a, scored august 14, 1911. 



Tem- 
pera- 
ture of 
curing 
reom 
8 a. m. 


Pale 
made. 


Cheese 
No.i 


Scored by U. S. Baer. , Scored by A. T. Briihn. 


Average. 


Fla- 
vor. 


Te.v- 
ture . 


Total. 


Flavor. 


Tex- 
ture. 


Total. 


Flavor. 


Tex- 
ture. 


Total. 


'F. 

67 

66" 

66' 

66" 

66" 

76' 

6S' 

66' 

66 


1911. 

Mav 22 

22 

2.5 

2.5 

29 

29 

June 1 

1 

2 

2 

7 

7 

9 

9 

13 

13 

15 

15 

16 

16 


230 
230C 

233 
2.33C 

234 
234C 

237 
237C 

238 
238C 

240 
240C 

242 
242C 

243 
2430 

245 
2450 

246 
2460 


43.0 
40.0 
41.0 
.38.0 
42.0 
39.0 
42.0 
35.0 
40.0 
37.0 
40.0 
33.0 
39.0 
39.0 
40.0 
.38. 
41.0 
37.0 
40.0 
40.0 


27.0 
26.0 
25.0 
25.0 
27.0 
25.0 
27.0 
25.0 
26.0 
26.0 
27.0 
25.0 
27.0 
26.0 
27.0 
25.0 
27.0 
26.0 
27.0 
26.0 


a5.o 

91.0 
91.0 
88.0 
94.0 
89.0 
94.0 
85.0 
91.0 
88.0 
92.0 
83.0 
91.0 
90.0 
92.0 
88. 
93.0 
88.0 
92.0 
91.0 


41.5 
37.0 
41.0 
36. 
42.0 
.37.0 
41.0 
38.0 
41.0 
37.0 
41.0 
37.0 
41.5 
.38.0 
41.0 
.38.0 
41.5 
40.0 
40.0 
39.0 


26.5 
25.0 
26.0 
25.0 
27.0 
25.0 
26.5 
26.0 
26.5 
25. 5 
26.0 
26.0 
26.0 
26.0 
26.0 
25.0 
27.0 
26. 
26. 
27.0 


93.0 
87.0 
92.0 
86.0 
94.0 
87.0 
92.5 
89.0 
92.5 
87.5 
92.0 
88.0 
92.5 
89.0 
92.0 
88.0 
93.5 
91.0 
91.0 
91.0 


42.25 
38.50 
41.00 
37. 00 
42.00 
38.00 
41.50 
36. 50 
40.50 
37.00 
40. 50 
35.00 
40.25 
38.50 
40.50 
38. 00 
41.25 
23. .50 
40.00 
39.50 


26.75 
25.50 
25.50 
25.00 
27.00 
25.00 
26.75 
25.00 
26. 2,5 
25.75 
26. ,50 
25., 50 

26. .50 
26.00 
26. 50 

25. 00 

27. 00 

26. 00 
26. 50 
26.50 


94.00 
89.00 
91.50 
87.00 
94.00 
S8.00 
93. 25 
87.00 
91.75 
87.75 
92.00 
85., 50 
91.75 
89.50 

92. 00 
SS.OO 

93. 25 
89.. 50 
91.. 50 
91.00 



LOT 4A, scored SEPTEMBER 18, 1911. 



68 


June 19 




19 


68 


21 




21 


70 


26 




26 


70 


27 




27 


70 


28 




28 


72 


July 3 




3 


72 


8 




8 


73 


10 




10 


73 


11 




11 


72 


V2 




]9 







248 
2480 

250 
2500 

253 
2530 

254 
254C 

255 
2.550 

258 
2580 

260 
260C^ 

261 
2610 

262 
2620 

263 
2630 



42.0 
40.5 
40.0 
37.0 
37.0 
35.0 
41.0 
3/.0 
41.0 
35.0 
40.0 
35.0 
41.0 
37.0 
40.0 
,38. 
41.0 
37.0 
40.0 
35.0 



27.0 


94.0 


42.0 


27.0 


94.0 


42.00 


27.00 


94.00 


26. 


91.5 


40.0 


26.5 


91.5 


40.25 


26. 25 


91.. 50 


26.0 


91.0 


41.0 


26. 5 


02.5 


40. 50 


26. 25 


91.75 


25.0 


87.0 


.38. 


2,5.0 


88. 


,37.50 


25.00 


87.. 50 


25.0 


87.0 


,39.0 


25.0 


89.0 


38.00 


25.00 


88. 00 


2,5.0 


85.0 


,35. 


26. 


86.0 


35.00 


25.. 50 


85.50 


27.0 


93.0 


41.0 


27.0 


93.0 


41.00 


27.00 


93.00 


26.0 


88. 


,37.0 


26.0 


88.0 


37.00 


26.00 


88. 00 


27.0 


93.0 


41.0 


27.0 


93.0 


41.00 


27.00 


93.00 


25.0 


85.0 


37.0 


25. 5 


87.5 


36.00 


25.25 


86. 25 


27.0 


92.0 


40.5 


26.5 


92.0 


40.25 


26.75 


92.00 


2.5.0 


85.0 


35.0 


25.0 


8,5.0 


35.00 


25.00 


85.00 


27.0 


93.0 


41.0 


26.5 


92.5 


41.00 


26.75 


92. 75 


2,5.0 


87.0 


36.0 


25.0 


86.0 


36. 50 


25.00 


86. .50 


25.0 


90.0 


,39. 5 


26.0 


90.5 


39. 75 


25., 50 


90.25 


27.0 


90.0 


,38.0 


27.0 


90.0 


38. 00 


27.00 


90.00 


27.0 


93.0 


41.0 


26.5 


92.5 


41.00 


26.75 


92.75 


26.0 


88.0 


37.0 


25.5 


87. 5 


37.00 


25.75 


87.75 


26.0 


91.0 


40.0 


26.0 


91.0 


40.00 


26.00 


91.00 


26.0 


86.0 


35.0 


26.0 


86.0 


35.00 


26.00 


86.00 



' "0'" in this column indicates raw-milk cheese. 

In 51 cases out of the 53 in the table the pasteiirized-milk cheese 
received a hio:her averacje total score than the raw-milk cheese; 
but in two cases the i-aw-milk cheese scored one-fourth to one- 
half a point hit^her (Xos. 183 and 184). In the 51 cases just 
mentioned the differences in total score between pasteurized and 
raw milk cheese ranged from one-fourth of a j-yoint to 7 points and 
averaged 3.82 points. In four-fifths of these cas-^s the difference in 
the score was over 2 points. In 49 of the 53 raw-milk cheeses the 
average score was below 92, while 39 of the 53 pasteurized-milk 
cheeses scored 92 or above. The distribution of the scores in each 
case is most clearly shown in figure 3. 



78 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



PA{STEUP/ZEO-M/LK CHESTSE 



>•: 



••• •••• •• 



It can readily be seen from figure 3 that 94 per cent (50 out of 53) 
of the pasteurized cheese scores lie between 91 and 95, a range of 4 
points, wliile the same proportion (94 per cent) of the raw-milk cheese 
scores are quite uniformly distributed between 85 and 92, a range of 
7 points. 

The variation in (piality of j)roduct from day to day is thus reduced 

nearly one -half by 
the new process. In 
scoring all of these 
cheeses the color and 
make-up were al- 
ways marked per- 
fect, and the cheeses 
were marked oft' 
only on flavor and 
texture. It is of in- 
terest therefore to consider the flavor and texture scores separately, 
in addition to the discussion of total scores given above. 

The average flavor score for all of the pasteurized cheese is 41.05 
and for the raw-milk cheese 38.13. In 50 cases out of 53 the pas- 
teurized-milk cheese has a higher average flavor score than the 
raw, in 2 cases the scores are ec^ual, and in 1 case the pasteurized 
cheese is one-fourth point less than the raw. 
In the 50 cases 



RAW-M/L/< CMETESE: 

! 



: i« 



as 86 87 ee 



89 90 9/ 9a 



93 9^ 9S 96 



Fig. 3. — Distribution of total scores of pasteurized and raw miiic clieese. 



P/iSr£U/?/2r£D''/^/^/t' CHeBSS 






•••• 



• • • 

{• ••• 
•• ••• 






just mentioned the 
difference in the fla- 
vor score between 
the two makes of 
cheese ranged from 
0.50 to 5.50 points, 
averaging 3.1 points. 
The difference was 
equal to or greater 
than 1.25 points in 
47 out of the 50 
cases, showing that 
the improvement in 
flavor through pas- 
teurization was not 
only unquestionable, but also consistent. In 51 out of the 53 cases 
the pasteurized-milk cheese scored 40 or above for flavor, while 45 
out of the 53 raw-milk cheese scored below 40 for flavor. 

Figure 4 shows that 94 per cent (50 out of 53) of the pasteurized 
cheese flavor scores lie between 40 and 42|^, a range of 2\ points; 
while the raw-milk cheese flavor scores are cjuite evenly distributed 



; : : 

• • • 

• • • 



: : 
i : 



• • • 
•••••••• 



36 37 



33 39 ^W -^ 



^2 43 



Fig. 4.— Distribution of flavor scores of pasteurized and raw milk 
cheese. 



PASriEUR/Z£:D-M/L/CCH££S£\ 



• • • t 

• • • • 

• •••••• 

• •••••• 



/^AW-M/LH' 
CH£ES£ 



• : : : 
: : : : 3 



2-? 2S 26 27 



CHEESE CURED IX THE SOUTH. 79 

over a raiifje of 5 ])oints (from l^f) to 40 or 41). The raiitjje of vuiia- 
tion is thus twice as orroat in the raw as it is in the pasteurized, show- 
ing that the (hiily variation of flavor is reducetl about one-lialf by 
the new })ro('ess. 

The averag<' texture seoi-es show also some advantage for the new- 
process cheese. The averag<' texture score on all of the pasteurized- 
milk cheese was 26.70, and on the raw-milk cheese 25. OB. 

In 40 cases out of 53 the pasteurized che(>se scored liiglier than the 
raw, in five cases the scores were equal, and in 8 cas(>s the pasteurized 
cheese scored 0.25 to 1.5 points (average 0.59 point) Iowcm- than the 
raw. Among the 40 cases just mentioned, tlu^ difrerences in t(\xture 
score between the two 
makes ranged from 
0.25 to 2 points, and 
averaged 1.09 points. 

Figure 5 shows that 
90 per cent (48 out of 
53) of the pasteurized- 
milk cheese texture 
scores lie between 26 
and 27.50. a range of 
1.50 points; wliile 94 
per cent (50 out of 53) 
of the raw-milk cheese 

scores are quite evenly distributed l)etween 25 and 27, a range of 2 
points, a distinct advantage^ in favor of the new })rocess, both as to 
quality and uniformity of texture. 

CHEESE CUKEl) IN THE SOUTH. 

Lot 75.— Foui- lots of cheese, lots IB, 2B, 3B, and 4B, were sliipped 
to New Orleans for storage, the first lot for two months and the other 
three for one month. 

Lot IB consisted of 25 pairs of cheese wliich were made on 25 days 
between February 23 and April 18, at Madison, and sliipped to New 
Orleans April 29, arriving May 9. They were stored theie until July 
3, and then shipped back to Madison where they were scored sepa- 
rately on July 17, 1911, by Messrs. U. S. Baer and A. T. Brulm. The 
temperatures at New Orleans given below are taken from the United 
States Weather Bureau monthly meteorological sunnnaries. The 
average daily mean for May was 75.8°, with temperature on different 
days varying from 60 to 96. For June the average daily mean was 
83^2°, with temperature on different days varying from 70 to 98. 
The quality of both the raw an(l pasteurized cheese after returning 
from New ()rleans was very poor, as shown by the scores of the judges 
and by letters from dealers to whom they were afterwards sold at a 



Fig. 0. — Distrituition of toxture scores of pasteurizod and raw milk 

clU'OSO. 



80 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



reduced price. The average score of the 25 pasteurized-milk cheeses 
was 85.10 and of the 25 raw-milk cheeses 83.34, a difference of 1.76 
points. In 17 cases out of 25 the pasteurized-milk cheese scored 
higher, in 3 cases equal to, and in 5 cases less than the raw-milk 
cheese. (See Table 40.) The highest average score given to any 
cheese in the lot was 90.5 and the lowest 78.50. The scores are 
shown in Table 40. 

Table 40. — Scores of 25 pairs of raw and pasteurized cheeses {lot IB) cured for two 
months at Neiv Orleans. 







Total 


Total 


AveraKe 
total 


Date made. 


Cheese 

No.' 


score 
(U. S. 


score 
(A.T. 






Baer). 


Bruhn). 


score. 


1911. 










Feb. 23 


171 


82 


SO 


81 


23 


1710 


87 


87 


S7 


24 


172 


83 


79 


SI 


24 


172C 


8.5 


81 


S3 


27 


173 


87 


90 


SS.5 


27 


173C 


8.5 


86 


8,5.5 


28 


174 


90 


S.5 


87.5 


28 


174C 


83 


8.5 


84 


Mar. 1 


175 


86 


S7 


86. 5 


1 


1750 


83 


84 


83.5 


2 


176 


86 


88 


87 


2 


1760 


83 


84 


83.5 


3 


177 


88 


84 


86 


3 


1770 


88 


8.5 


86.5 


7 


178 


86 


86 


86 


7 


1780 


86 


8.5 


8,5.5 


S 


179 


91 


90 


90.5 


8 


1790 


85 


S3 


S4 


9 


ISO 


86 


SS 


87 


9 


ISOO 


a5 


8,5 


85 


10 


ISl 


90 


SS 


89 


JO 


1810 


85 


8,5 


85 


13 


182 


SO 


SO 


80 


13 


1820 


80 


SO 


80 


14 


183 


79 


79 


79 


14 


1830 


87 


84 


&5.5 


15 


184 


8,5 


84 


84.5 


15 


1840 


8.5 


82 


83.5 


16 


185 


85 


89 


87 


16 


1850 


85 


S.5 


85 


17 


186 


80 


80 


SO 


17 


1860 


80 


80 


80 


20 


187 


79 


80 


79.5 


20 


1870 


79 


80 


79.5 


21 


188 


77 


80 


78.5 


21 


1880 


80 


80 


80 


22 


189 


86 


83 


84.5 


22 


1890 


80 


80 


SO 


Apr. 5 


198 


92 


89 


90.5 


5 


1980 


89 


81 


85 


7 


200 


86 


87 


86.5 


7 


200O 


82 


85 


8.3.5 




202 


85 


88 


86.5 




2020 


83 


84 


8.3.5 




204 


89 


87 


88 




204O 


84 


84 


84 




206 


89 


86 


87.5 




206O 


83 


81 


82 


18 


207 


85 


86 


8,5.5 


18 


207O 


83 


84 


83.5 



i <' C" in this column indicates raw-milk cheese. 



CHEESE CURED IX THE SOUTH. 81 

It can be seen that storage lor so long a period as Uvo months in 
New Orleans, at. such teraperatnres, can not be i)racticed with either 
raw or pasteurized cheese without great loss of quahty; and that of 
the two lots, the pasteurized was somewhat the better when taken 
out of storage. On account of the unmarketable quahty of both lots 
of cheese when scored it appears unnecessary to give the detailed 
score and criticisms as to flavor and texture. 

Lots 2B, SB, and 4B. — These lots were stored at New Orleans for one 
month each during parts of June, July, August, and Sei)teml)er, 1911 . 
The mean daily tempera tm-e during this jx'riod averaged 83.2° for 
June, 80.2° for July, 81 .8° for August, and 82.6° for September. In 
lot 2B the 9 pasteurized-milk cheeses received an average total scoi-e 
of 90.44, and the raw-milk cheese of 85.56. The pasteurized was 
better in every case, and on the av(M'age 4.88 ])oints better. 



PASrEU/?/ZEO-M/L/< CHEESE^ X 

• • • : : • : ::::;•::: 


• * • • ••• 


• • 


RA{A/-A7/L/< CHEESE 

• 

• 

• • 

• • • •• ••• 


• • • • 

• • • • 

• • • • • 






77 78 79 80 81 82 


83 8f 85 86 87 88 89 


90 91 92 


93 



l''!i;. ii.--l)i.stril.)Uliiiii of tcital scores of pastctiriziMl and raw milk clict'sc. 

In lot 3B the 10 piisteurized-milk cheeses scored the highest in 
every case, the average being 7.7 i)oints higher. The average score of 
the pasteurized was 90.30, and of the raw 82.60. 

In lot 4B the 10 pasteurized-milk cheeses scored th(>, highest in 
every case but one, and averaged 85.62, while the 10 raw-milk 
cheeses averaged 82.10, a difference of 3.52 points. 

From the results shown in Tables 40 and 41 and in ligure 6, it is 
clear that after storage in the South the pasteurized-milk cheese 
came out better in quality than the raw-milk cheese made from the 
same milk. It is not intended to suggest that cheese could be shipped 
to the Southern States with the exi)ress intention of storing it for one 
month before it is sold, but it is clear that during the few days or 
Weeks necessarily elapsing after market cheese reaches its destination 
in the South and before it is eaten, the pasteurized-milk cheese is 
less likely to undergo serious deterioration than the raw-milk cheese. 
79994°— Bull. 165—13 tj 



82 



CHEDDAR CHEESE FROM PASTEURIZED MILK. 



Table 42. — Scores of 29 pairs of raw and pasteurized cheeses {lots JB, 3B, and 4B) cured 
for one month at New Orleans. 

LOT 2B, SCORED JULY 17, 1911, AT MADISON. 



Date made. 


Mean 
tempera- 
ture at 
New 
Orleans. 


Cheese 
No.i 


Total 
score 
(U.S. 
Baer). 


Total 

score 

(A. T. 

Bruhn). 


Averas;e 
total 
score. 


1911. 

Apr. 24 

24 

27 

27 

28 

28 

May 2 

2 

3 

3 

:^ 

in 
in 

15 
15 
17 
17 


'F. 

46 


211 
2110 

214 
2140 

215 
215C 

216 
2160 

217 
2170 

220 
220O 

222 
2220 

225 
2250 

227 
2270 


90 

8.5 
92 
85 
93 
85 
90 
85 
91 
8.5 
90 
85 
92 
88 
89 
87 
92 
86 


88 
86 
90 
86 
90 
84 
88 
86 
89 
8.5 
87 
58 
, 94 
87 
91 
85 
92 
85 


89 

85.5 

91 

&5.5 

91.5 

84.5 

89 

8,5.5 

90.0 

8,5 

88,5 

85 

93 

87.5 

90 

86 

92 

85.5 


CO 


55 


66 


m 


71 


73 


76 


76 





LOT 3B, SCORED AUG. 14, 1911, AT MADISON. 



May 22 

22 

25 

25 

29 

29 

June 1 

1 

2 

2 

7 
9 
9 
13 
13 
15 
15 
16 
16 


78 


230 
2.300 

233 
2330 

234 
2340 

237 
2370 

238 
2380 

240 
2400 

242 
2420 

243 
2430 

245 
2450 

246 
2461' 


89 
83 
90 
79 
91 
S3 
91 
SO 
91 
8.5 
92 
80 
93 
82 
92 
86 
90 
87 
89 
86 


SS 

84 

88 

80 

99 

82 

90 

81 

90 

82 

89 

79 

92,5 

SI 

90,5 

85 

91 

85 

89 

S2 


88.5 
83. 5 
89 
79.5 
90. 5 
82. 5 
90. 5 
.80. 5 
90.5 
83. 5 
90. 5 
79.5 
92. 75 
SI. 5 
91.25 
,8,5. 5 
90.5 
86 
89 
84 


82 


S4 
'.86 


8j 


8 i 


87 


88 


88 


86 





LOT 4B, SCORED SEPT. 18, 1911, AT MADISON. 



June 19 

19 

21 

21 

26 

26 

27 

27 

28 

28 

Julv 3 

3 

8 

8 

10 

10 

11 

11 

12 

12 


76 


248 
2480 

250 
2500 

2.53 
2530 

2,54 
2540 

255 
2550 

258 
2580 

260 
260O 

261 
2610 

262 
2620 

263 
2630 


88,5 

83 

81 

85 

87 

87 

89 

76 

80 

78 

8.5 

82 

88 

86 

62 

79 

90 

a5 

87 
80 


87 
8.5 
82 
8,5 
88 
85 
89 
78 
80 

S>i 
85 
88 
83 
80 
78 
89 
8,5 
86 
80 


87,75 

84 

81.5 

85 

87.5 

86 

89 

77 

80 

77.5 

.85.5 

83.5 

88 

84.5 

81 

78.5 

89.5 

85 

86.5 

80 


74 


80 


82 


80 


82 


79 


82 


82 


79 





» "0" indicates raw-milk cheese. 



CHEESE CURED IN THE SOUTH. 



83 



Lots 30 and J^C. — These two additional lots were stored for one 
month in the South and subsequently scored at Madison. In lot 
3C the 10 pasteurized cheeses averaged 91 and the 10 raw-milk 
cheeses 84.85, as shown in Table 42. In every case the pasteurized 
cheese scored higher than the raw. In Lot 4C, the 10 pasteurized 
averaged 87.82 in total score, and the 10 raw-milk cheeses, 85.07, and 
in every case but one the pasteurized scored higher than the raw. 
All but two of these 40 cheeses scored below 92 and most of them were 
unsalable at full ])rice, after storage as described. The temperature 
inside of the storage warehouse was not recorded. 

Table 42. — Scores of 20 pairs of raw and pasteurized milk cheese (lots SC and 4C) stored 
one month in the South and scored at Madison. 

LOT 3c, STORED ONE MONTH AT COLUMBUS, GA., AND SCORKD AT MADISON, AUG. 14, IQU. 



Date 
made. 


Cheese 
No.' 


Total spore 
(O. s. 
Baer). 


Total score 
(A.T. 
Bruhn). 


Averagp 
total score. 


19U. 










Apr. 22 


2.'!0 


00 


90 


90 


22 


ZiOr 


S7 


8ti 


Sf>. 5 


25 


233 


90 


89J 


89. 75 


25 


2330 


85 


84 


84. 5 


29 


234 


94 


94 


94 


29 


2340 


91 


87 


89 


JUTIP 1 


237 


92 


89 


90. a 


1 


237(^ 


85 


83 


84 


2 


238 


90 


91 


iK). 5 


2 


2380 


84 


S5 


84. 5 


7 


240 


92 


91 


91.5 


7 


240O 


78 


79 


78.5 


9 


242 


91 


93 


92 


9 


2420 


85 


87 


86 


1.3 


243 


Lost.. 


Lost. 


Lost. 


1.-? 


24M • 


S5 


S2 


83.5 


15 


245 


91 


90 


i»0. 5 


15 


245(': 


89 


84 


86. 5 


16 


246 


<M 


90i 


90. 25 


16 


246C 


88 


83 


85.5 



LOT 4C, STORED ONE MONTH AT NEW ORLEANS, AND SCORED AT MADISON, SEPT. 18, 1911. 



I9I1. 










June 19 


248 


90 


m, 


SO. 75 


19 


2481' 


85 


86' 


85. 5 


21 


250 


88 


S8 


88 


21 


2.50(' 


85 


85 


85 


26 


2.53 


86 


87 


S(i. 5 


26 


253(^. 


86 


85i 


85. 75 


27 


254 


90 


S9i 


89. 75 


27 


254(': 


80 


83 


81.5 


28 


255 


89i 


891 


89.5 


28 


2550 


&3 


85" 


84 


,Tulv 3 


258 


87 


88 


87.5 


3 


2580 


86 


86 


86 


8 


260 


89 


90 


89. 5 


8 


2600 


87 


86 


86.5 


10 


261 


83 


84 


8:^.5 


10 


2610 


87 


86 


86.5 


11 


262 


85 


85 


85 


11 


2620 


85 


85 


85 


12 


263 


90 


88i 


89. 25 


12 


263C 


85 


85 


85 



1 "C'- indicates raw-milk cheese. 



84 



CHEDDAR CHEESE FEOM PASTEURIZED MILK. 



CHEESE CURED IN WARM ROOM AT MADISON. 

Lots 3D and ^D. — These lots of cheese were stored in a warm room 
at Madison wliere the temperature ranged from 70° to 80°, occasion- 
ally going up to 85°, during the months of July, August, and Septem- 
ber, 1911. In lot 3D the pasteurized cheese scored higher than the 
raw-milk cheese in every case, averaging 90.55 to total score, while 
the raw-milk cheese averaged 83.75. In lot 4D the j^asteurized cheese 
scored higher than the raw in every case but one, averaging 90.52, 
while the raw-milk cheese averaged 86.15, as shown in Table 43. 



Table 43.- 



-Scores of 20 pairs of rmv and pasteurised milk cheese {lots 3D and 4D) stored 
in warm room at Madison. 



LOT 3d, scored AUG. 14, \9U. 



Date 


Cheese 


Total score 
(U.S. 
Baer). 


Total score 
(A. T. 
Bruhn). 


Average 


made. 


No.i 


total score. 


1911. 










May 22 


230 


87 


87 


87 


22 


230C: 


85 


86 


85. 50 


2.5 


233 


90 


S9J 


89. 75 


2,1 


233C 


81 


80 


SO. .50 


29 


234 


93 


94 


03. 50 


29 


2340 


85 


85 


85 


June 1 


237 


94 


94 


94 


1 


237('. 


80 


SO 


SO 


2 


23<S 


90 


91 


90. 5 


2 


23sc: 


85 


86 


85. 5 


7 


240 


94 


94 


94 


7 


240C 


79 


79 


79 


9 


242 


92 


92.\ 


92. 25 


9 


2420 


85 


85 


S5 


13 


243 


90 


89 


89. 5 


13 


2430 


85 


86 


85. 5 


15 


245 


87 


88 


87. 5 


15 


2450 


85 


86 


85. 50 


If) 


"46 


SS 


87 


87.5 


16 


2460 


87 


85 


86 



LOT 4D, .SCORED .SEPT. 18, 1911. 



June 19 


248 


91 


9U 


91.75 


19 


2480 


85 


85 


85 


2! 


250 


86 


86 


86 


21 


250C 


86 


85 


85. 50 


26 


253 


88 


88 


88 


26 


2530 


85 


86 


85.5 


27 


254 


91 


92 


91.5 


27 


2540 


80 


82 


81 


28 


255 


92 


924 


92.25 


28 


2550 


89J 


m 


89.5 


July 3 


258 


92 


92 


92 


3 


2580 


87 


86 


86.5 


8 


260 


91 


92 


91.5 


8 


2600 


86 


S6J 


86.25 


10 


261 


85 


85 


85 


10 


2610 


89 


87 


88 


11 


262 


94 


94 


94 


11 


2620 


86 


88 


87 


12 


263 


93 


93 


93 


12 


2630 


86 


89 


87.5 



i"C" indicates raw-milk cheese. 



CHEESE CURED IX COLD STORAGE. 



85 



CHEESE CURED IN COLD STORAGE. 

Lot 4E. — Siiicp iinich of llie clioeHo made by the onliiuiry ])rocess 
is put into cold storage at about 'A4°, and most cheese dealers Jiave 
cold-storage warehouses, a study was begun of the effect of cold 
storage on pasteurized-milk cheese. The milk supply was so short 
at the time that raw-milk cheese could be luade on oidv a few days. 
Six or seven pasteurized-milk cheeses were made in one vat each day 
and placed in the curing room at Madison, and single cheeses were 
s]ii])])e(i to a cold-storage warehouse at Waterloo, \Vis., at diff(M'ent 
ages. After about three montlis the chcf^se was ail sliipped back to 
Madison in one consiginuciit and ('.xaiiiined by the judges. One 
(•]i>('se fi'om cacli day's juake was ke])t at Madison (hiring the entire 
])erio(l. 

Table 44. — Scores of pasteurized and raw mill: cheese (lot -'{E) put into cold storage at 
different ayes and scored Oct. ,iO, 1911. 









Scored bv U. S. 


Scoied bv A. T. 






1 






Age 
when 
stored. 




Baer. 






Hruhn. 




Average score. i 


Date 
iiiiide. 


Chease 

No.' 






















Tex- 
ture. 






Te.x- 

ture. 
















Flavor. 


Total. 


Flavor. 


Total. 


Flavor. 


Tex- 
ture. 


Total. 


19n. 
























July 20 
20 


264. 1 
264.2 




42. 00 
41.00 


28.00 
26. 50 


95. 00 
92. .50 


42. .50 
40. .W 


27. 00 
27. 00 


94. 50 
92. 50 


42. 25 
40.75 


27.50 
26. 75 


94.75 
92. 50 


1 day — 


20 


264. W 


1 week . . 


40. (K) 


26. 00 


91 . 00 


40. 50 


27. 00 


92. 50 


40. 25 


26. 50 


91.75 


20 


264.4 


2 weeks. 


41.00 


28. 00 


94. 00 


41.00 


27. .50 


93. 50 


41.00 


27. 75 


93. 75 


20 


264. 5 


4 weeks. 


41.00 


2S. (H) 


94. 00 


42. 00 


28. 00 


95. 00 


41., 50 


28. 00 


94. 50 


20 


264.6 


6 weeks. 


41.00 


2.S. 00 


94.00 


42. 00 


27.50 


94.50 


41. 50 


27.75 


94. 25 


20 
21 


265. 1 
265. 2 




41. 00 
40.00 


27. (H) 
27. 00 


93. 00 
92. 00 


41.00 
41.00 


26. ,50 
26. 50 


92. 50 
92.50 


41.00 
40.50 


2(i. 75 
26. 75 


92. 75 
92. 25 


"idayV.".. 


21 


265. 3 


1 week . . 


42. 00 


28.00 


95. 00 


42.00 


28. (X) 


95. 00 


42.00 


28. 00 


95. 00 


21 


265. 4 


2 weeks. 


40. 00 


27.00 


92. 00 


40. 00 


27.00 


92.00 


40. (X) 


27. 00 


92. 00 


21 


265. 5 


4 weeks. 


4(1 00 


27.00 


92. 00 


40. 00 


27. 00 


92.00 


40.00 


27.00 


92.00 


21 


265. 6 


4 weeks. 


40. 00 


27. 00 


92. 00 


41.00 


27. 00 


93.00 


40. .50 


27.00 


92. 50 


25 


265.7 


6 weeks. 


41.00 


28. 00 


94. 00 


42. 00 


27.00 


94.00 


41., 50 


27. 50 


94.00 


25 
25 


267. 1 
2t)7. 2 




41.00 
40. 00 


28. IX) 
26. 00 


94.00 
91.00 


42.00 
40. 00 


27. 00 
26. 00 


94.00 
91.00 


41.. 50 
40. 00 


27. 50 
26. 00 


94. 00 
91.00 


1 day 


25 


267. 3 


1 week . . 


41. 50 


27. 00 


93. 00 


41.50 


27. 50 


94. (X) 


41.. 50 


27. 25 


93. 75 


25 


267. 4 


2 weeks. 


40. 00 


27. 00 


92.00 


41.00 


27. 00 


93. 00 


40. 50 


27.00 


92.50 


25 


267.5 


4 weeks. 


41.00 


27. 00 


93. 00 


40. 50 


27. 00 


92. 50 


40. 75 


27.00 


92.75 


25 


267.6 


6 weeks. 


42. 00 


27.00 


94.00 


42. 00 


27. .50 


94.50 


42. 00 


27. 25 


94.25 


25 


267('l 




36. 00 


26.00 


87.00 


36. 00 


26. 50 


87. .50 


36. 00 


26.25 


87.25 


25 


267C2 


i (iay 


38. no 


27.00 


90. 00 


39. 00 


27.00 


91. 00 


38. 50 


27. 00 


90.50 


25 


267('3 


2 weeks. 


38. 00 


27.00 


90. 00 


38. 50 


27.00 


90.50 


3S. 25 


27.00 


90. 25 


27 
27 


269.1 
269. 2 




40. 00 
40. 00 


27. 00 

27. 00 


92. 00 
92.00 


41.00 
40. 50 


26.50 
26. .50 


92.50 
92.00 


40.50 
40. 25 


26.75 
26. 75 


92. 25 
92.00 


1 day — 


27 


269. 3 


1 week . . 


40. 00 


27.00 


92. 00 


40. 50 


26.50 


92. 00 


40. 25 


26.75 


92.00 


27 


269.4 


2 weeks. 


41.00 


27. 00 


93. 00 


40. 00 


26,50 


91.50 


40. 50 


20. 75 


92. 25 


27 


269.5 


4 weeks. 


41.00 


27.00 


93. 00 


42.00 


27. 00 


94.00 


41. .50 


27. 00 


93. 50 


27 


269.6 


6 weeks. 


42. 50 


28.00 


95. 50 


42. 50 


27.50 


95. 00 


42.50 


27.75 


95.25 


27 


269C1 


2 weeks. 


34.00 


23. 00 


82.00 


32.00 


25. (X) 


82. 00 


33. (X) 


24. (K) 


82. 00 


Aug. 1 
1 


272.1 
272.2 




35. 00 
36.00 


23. 00 
25.00 


83.00 
86.00 


36. 00 
36.00 


25. 00 
25. 00 


86.00 
86.00 


35.50 
36.00 


24. 00 

25. 00 


84. ,50 
86.00 


1 day — 


1 


272.3 


1 week.. 


37. 00 


25. 00 


87. 00 


.39. 00 


24.00 


8.S.0O 


38.00 


24. 50 


87. 50 


1 


272.4 


2 weeks. 


38.00 


2.5.00 


88.00 


38.00 


25.00 


88.00 


38.00 


25. 00 


88. 00 


1 


272.5 


4 weeks. 


35. 00 


25.00 


85.00 


36. 00 


24.00 


85.00 


35. .50 


24. 50 


85. 00 


1 


272.6 


6 weeks. 


37. 00 


24. 50 


86. 50 


38. 00 


25.00 


88.00 


37.50 


24. 75 


87. 25 


8 
S 


276.1 
276. 2 




37.00 
40. 00 


25. 00 
26.00 


87. 00 
91.00 


39. 00 

40. 00 


26. 00 
26. 00 


90.00 
91.00 


38.00 
40. 00 


25.50 
20.00 


88. .50 
91.00 


1 day — 


8 


276.3 


1 week.. 


40. 00 


25. 00 


90. 00 


39. 50 


25. 50 


90.00 


.39. 75 


25. 25 


90. 00 


8 


276.4 


2 weeks. 


40.00 


24.00 


89. 00 


39. 00 


25. 00 


89.00 


39.50 


24. 50 


89.00 


8 


276.5 


4 weeks. 


40. 00 


27.00 


92. 00 


39. 50 


26. 50 


91.00 


39.75 


26.75 


91. 50 


22 
22 


283. 1 
283. 2 




41.00 
40.00 


27.00 
26.00 


93.00 
91 . 00 


41.. 50 
40. ha 


26. .50 
26.00 


93.00 
91.50 


41.25 
40.25 


26. 75 
26. 00 


93.00 
91.25 


1 day 


22 


283.3 


1 week.. 


42.00 


27.00 


94. 00 


41.00 


27.00 


93. 00 


41.50 


27.00 


93.50 


22 


283. 4 


2 weeks. 


40.50 


27.00 


92.50 


41.00 


26. 50 


92.50 


40.75 


26. 75 


92.00 


22 


283.5 


4 weeks. 


42.00 


27.00 


94.00 


41. 50 


27.00 


93. 50 


41.75 


27. 00 


93.50 


22 


283. 6 




42.00 


27.00 


94.00 


42.00 


2(). 50 


93. 50 


42.00 


26. 75 


93.75 





> "C" in this column indicates raw-milk cheese. 



86 



CHEDDAK CHEESE FROM PASTEURIZED MILK. 



In every case the pasteurized-milk oheese put into cold storage at 
the age of one day was criticized by the judges as being flat, low, and 
not developed in flavor, and the texture was described as curdy, new, 
not broken down, not cured, etc. They received an average score 
of 90.84, as shown in Table 44. 

The cheeses put into cold storage at the age of one week received 
an average score of 91.93. They were found to be weU cured, and 
they had less mold on the surface (practically none), both when put 
into storage and when taken out, than any of the later lots. The 
cheeses put into storage at two weeks, four weeks, and six weeks of 
age were given average scores of 91.36, 91.82, and 91.46, respectively, 
while those kept at Madison for the entire period scored 91.39. 

So far as this short series indicates, there is no objection to putting 
pasteurized-milk cheese into storage at 34°, at the age of one week, 
immediately after paraffining. It was planned, however, to make a 
more extensive trial of the use of cold storage for pasteurized-milk 
cheese during the season of 1912. 



EXCEPTIONAL DIFFERENCES BETWEEN THE RAW AND PASTEURIZED MILK CHEESE. 

It is of interest to coUect in one pkice all of the cases recorded in 
the tables where the pasteurized-milk cheese was scored lower than 
the raw, in order if possible to locate the cause for such difi^erence. 

Table 45. — Summary of cases in which raw-milk cheese scored higher than pasteurized. 



LotslA,2A,3A,4A. 


LotslB,2B,3B,4B. 


Lots 30, 40. 


Lot? 3D, 4D. 


Cheese 
No.i 


Total 
Score. 


Cheese 
No.' 


Total 
Score. 


Cheese 
No.' 


Total 
Score. 


Oheese 
No.' 


Total 
Score. 






171 
2 171C 

172 
2 172C 

177 
« 177C 

183 
2 1830 

184 
1840 

188 
2 1880 

250 
2 250O 

261 
2610 


81.00 
87.00 
81.00 
83.00 
86.00 
86.50 
79.00 
85.50 
84.50 
83.50 
78.50 
80.00 
81.50 
85.00 
81.00 
78.50 






















172 
172C 

177 
177C 

183 
2 183C 

184 
2 184C 

188 
188C 

250 
250C 

261 
2610 


91.75 
89. 51) 
91.75 
89.00 
91.25 
91.75 
92.00 
92.75 
94.50 
90.50 
91.75 
87.50 
90.25 
90.00 


















































































250 

250C 

261 

2 2610 


88.00 
85.00 
83. 50 
86.50 


250 

250C 

261 

2 2610 


86.00 
85.50 
85.00 
88.00 



• "0" indicates raw-milk cheese. 

« These are the cases in which the raw-milk cheese scored higher than the pasteurized. 
of duplicate cheese in the other lots are given for comparison. 



The other scores 



The fact that pasteurized and raw cheese from the same milk may 
occasionally score exactly alike or nearly alike would appear to indi- 
cate that where the milk supply is excellent the quality of cheese pro- 
duced is not improved by the new process. With so small a differ- 
ence in score as half a point, occurring in No. 184 in lot A and No. 



DISCUSSION OF CHEESE SCORES. 87 

177 in lot B, it is doubtful whether there was any difference between 
the two cheeses which could be ascribed with certainty to the effect 
of the pasteurization process. 

The most adverse criticism on the process that can be based upon 
the 10 cases tabulated above is the following: It is entu-ely possible 
that some harmful bacteria or thou- cnzyms which arc occasionally 
present in dirty milk may not be destroyed by the pasteurization 
process and that such infections damage the quality of pasteurized- 
milk cheese as well as raw^-milk cheese. In this year's work it has 
been noticed that on a few occasions when the raw milk was very ripe 
the quality of cheese produced, even after j)asteurization, was not so 
good as from milk of fairly good quality. For example: The poorest 
pasteurized-milk cheese in Table 45 is No. 201, and the milk used for 
making this was of 0.28 i)er cent acidity before pasteurization. In 
Table 44, showing the scores of cheese shipped to cold storage, Nos. 
272 and 276 are the poorest in quality and these were made from milk 
which titrated 0.275 and 0.31 per cent acidity, res})ectively, before 
pasteurization. Of course such milk should not be accepted at any 
cheese factory. 

No claim is made that the pasteiu'ization process is a cure for all 
the troubles of the cheese factory, or that it reduces the responsibility 
resting on factory patrons to improve the sanitary quality of their 
milk. It would, in fact, be most unfoi'tunate if any process coidd 
be used for making cheese, or any other article of food, which would 
relieve the milk producer or the factory man of the necessity for 
cleanliness. 

SUMMARY OF DISCUSSION OF SCORES, 

The scores of lots IB, 2B, 3B, and 4B, 3C and 4C, and 8D and 4D 
all show that cheese, either raw or pasteurized, stored for one or two 
months at about 80° are often seriously injured, so as to be unsalable 
at the ruling market price. The pasteurized cheese came out of 
such storage better in quality than the raw-milk cheese in about 90 
per cent of all the cases observed. It is clear that pasteurized-milk 
cheese is better suited to stand exposure to high temperature than 
raw-milk cheese. This fact may find useful application in two ways: 
Wliile it is never advisable to store market cheese for any great 
length of time in the South, yet several days or weeks may often 
elapse before cheese shi])ped South is finally sold to the consumer, 
and it appears that })asteurized-milk cheese shoidd stand this ex- 
posure with less damage in quality thair raw-milk cheese. It is 
likely, too, that ])asteurized-milk cheese can be cured at ordinary 
curing-room temperatures below 70° in Wisconsin without the use 
of ice or mechanical refrigeration, thus avoiding part of the expense 
for cold storage. The quality of the 53 raw-milk cheeses in lots lA, 
2A, 3A, and 4A, cured at 60° to 73° at Madison, is represented by the 



88 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

average total score of 89.09, and would no doubt have been greatly 
improved if the cheese had been cured in cold storage. In 51 cases 
out of 53 the pasteurized-milk cheese in these lots scored higher 
than the raw, on the average 3.8 points higher, the average total 
score of the pasteurized being 92.75 points, which indicates that cold 
storage for the pasteurized cheese was not necessary. 

In a short series of cheese placed in cold storage at 34° F. at dif- 
ferent ages, it was found that those stored at the age of one day were 
curdy and uncured at the age of three months, wliile those placed in 
storage at the age of one week were free from this fault and scored 
as high, even a little higher, and showed less mold on the surface 
than those put in storage when older than one week. From this it 
appears that pasteurized-milk cheese can be safely put in cold storage 
at the age of one week immediately after i)araffining. It was planned 
to try cold storage with both raw and pasteurized-milk cheese 
during 1912. 

THE DEMAND FOR PASTEURIZED-MILK CHEESE. 

One of the objects of the work during 1909, 1910, and 1911 was to 
sell the cheese to consumers as widely as possible, and learn whether 
it would meet with favor and continued demand. It' was felt neces- 
saiy thus to establish its suitability for the market before recom- 
mending cheese makers to take up the new process. 

The amount of pasteurized-milk cheese sold each year was limited 
by the output of the factory, it being impossible to secure a larger 
supi)ly of milk. Much more cheese could have been sold to the 
same purchaseis, and doubtless to others, if we had had the cheese 
to sell. In nearly all cases the cheese was sold at the current price 
ruling on the Plymouth cheese board, f. o. b. Madison without 
discount. During 1910, 4,815^ pounds of pasteurized-milk cheese 
valued at $711.16 were sold to 19 representative grocery stores, 
hotels, restaurants, and delicatessen stores in Madison, Wis, The 
total number of such sales was 137 during the season. Nearly 
every purchaser reordered it several times, and three of the leading 
retailers reordered it 15, 20, and 49 times, respectively, during the 
season. The average price paid for all of tliis cheese was 14f cents 
per pound. During 1909, 1910, and 1911, 41 shipments of pasteur- 
ized-milk cheese weighing 10,126 pounds in all and valued at $1,382.93 
were sent to 27 leading cheese dealers, including a few retail stores, 
at New York, Boston, Philadelphia, Chicago, St. Louis, IVIinneapolis, 
and San Francisco, and at various Wisconsin points outside of 
Madison, including Plymouth, Sheboygan, Fond du Lac, Marshfield, 
Richland Center, Waterloo, and Milwaukee. Samples of the cheese 
were also shipped to experiment station workers in the leading dairy 
States for an examination. 



EXTRA COST OF PASTEURIZED-MILK CHEESE. 89 

OPINIONS OP PURCHASERS. 

No written opinions were asked from dealers in Madison handling 
the pasteurized-milk cheese, neither were they urged to purchase a 
second time. The university <h-livery wagon making two tri])s 
daily among retail stores took such orders as w^ere given. The fact 
that a dealer bought this make of cheese only once may be due to a 
variety of causes, such, for example, as business relations with other 
wholesale cheese dealers in the city. The fact that several of the 
leading grocers sold this cheese continuously for several months and 
repurchased it every week or oftener, and always without I'eporting 
any complaint from consumers, is taken to indicate that it was 
satisfactory to the retail trade of this city. 

An effort was made to obtain a written opinion from every firm 
outside of Madison to whom the cheese were sold. It was usually 
impossible to send many shij)ments to a single ])urchaser, because 
it was desired to distribute the available suppl}' of cheese as widely 
as ])ossible. 

The letters received from dealers outside of Madis(m show that all 
except a very few found the cheese to be entirely satisfactory, and 
salable at the full market price. Here again the occasional disap- 
proval of a cheese may be due to an oversupply in the buyer's ware- 
house, or other causes than the quality of the cheese iteslf. It is 
mteresting to note that ])asteurized-milk cheese shipped to two firms 
who apparently disliked it was the same day's make as others shipped 
on the same date to three other firms who praised their quality and 
pronounced them satisfactory. In every case dealers were informed 
that the cheese "was made by special process, which we are tryino- 
at Madison, by which it is hoped that cheese of cleaner flavor and 
greater uniformity can be obtained. " In no case were dealers in- 
formed as to the nature of the ])rocess or that the milk was pasteur- 
ized. The purpose was to excite the dealers' interest and secure 
careful examination of the cheese, unqualified by any prejudice for 
or against pasteurization. 

The very general expression of approval of the product in the let- 
ters from dealers and experiment stations appears to warrant fur- 
ther trial of the method on a larger scale than heretofore. 

THE EXTRA COST OF MAKING PASTEURIZED-MILK CHEESE. 

While it has been shown that an increased yield of cheese is ob- 
tained there are also additional costs, which must be charged agamst 
the cheese made by this method. Such costs will include the interest 
on investment, and depreciation, of a pasteurizer, cooler, and receiv- 
ing vat, a charge for the hydrocliloric acid used and for the expense 
of steam heat and power for pumping water for cooling the pasteur- 
ized milk, and for running the pasteurizer. 



90 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

Preliminary estimates, based upon available data, seem to indicate 
that the extra cost of making pasteurized-milk cheese is less than the 
additional value of the cheese, leaving a net profit from the use of the 
process, as compared with the regular factory process. Since the 
steam and water supplies used in the work at Madison were drawn 
from the general service pipes of the Wisconsin Agricultural Experi- 
ment Station it was impossible to determine these items of cost with 
exactness. 

In order to ascertain precisely what the charges for steam heat, 
power, etc., are at an average cheese factory in Wisconsin, a com- 
plete outfit for making pasteurized-milk cheese will be set up at a 
country cheese factory, easily accessible from Madison, and operated 
by an experienced and successful cheese maker. Cheese will be made 
there by both the regular factory method and by the new method in 
order to ascertain more fully the cost of making, the increased yield, 
and the market value of pasteurized-milk cheese. 

FURTHER TRIALS OF THE NEW PROCESS IN CHEESE FACTORIES, 

The results described in this bulletin appear to indicate that the 
new method of cheese making is an improvement over the regular 
process now commonly used. Working with the milk supply avail- 
able at Madison, the new method is unquestionably an improvement 
over the old. It is a fact well known to cheese makers, however, that 
the milk supplies found at different factories do not always behave 
alike in the cheese vat, so that the old process must frequently be 
modified to suit the conditions encountered in different localities. It 
remains, therefore, to test the new method at several factories in dif- 
feront cheese-making districts before it can be recommended for use 
generally. Cheese makers are advised to await the publication of 
results of further trials before undertaking to use the new method on 
a commercial scale. 

It is hoped that the new method will receive careful attention and 
criticism by such cheese experts at experiment stations in different 
parts of the country as may be able to give it a trial. The authors 
will be glad to correspond with any one interested and to aid in such 
trials so far as circumstances permit. 

SUMMARY. 

PRELIMINARY AND COMPARATIVE WORK WITH THE OLD AND NEW 

METHODS. 

The contmued improvement of the cheese-making industry calls for 
more economical factory management. Large, well-equipped facto- 
ries should replace many of the small, poorly supported factories of 
the present time. 



SUMMARY. 91 

To enable cheese factories to handle milk from larger areas of ter- 
ritory, and for other reasons also, a new method of cheese making is 
needed by means of which milk of variable quality from many farms 
can (1) be brought into practically uniform condition for cheese 
making at the factory, and (2) can be made up into cheese in a uni- 
form, routine manner daily without variations of time or method of 
handling; also (3) cheese of greater uniformity should be produced, 
and (4) the losses in yield and quality of cheese due to defective milk, 
now common in factories, should be avoided. 

During the years 1905 and 1906 experimental cheese was made 
without starter, addhig in its place to the raw milk some commercial 
acid, as hydrochloric acid or other kinds. The method of adding the 
acid to milk was perfected, and a two weeks' trial of the process was 
finally made in a commercial factory at Muscoda, Wis. It was shown 
clearly that the addition of hydrochloric acid to milk in a cheese fac- 
tory is entirely practicable and that the quality of the cheese is not 
hi any way injured by such addition, but it was also found that the 
((uality of cheese obtained from oven-ij)e or tainted milk was no bet- 
ter than by the use of the ordinary factory methods. Therefore, 
there was no reason for recommending the use of hydi'ochloric acid to 
cheese makers at that time. 

Most of the defects observed in cheese-factory milk are of bacterial 
origin, and in other branches of the dau-y industry pasteurization is 
successfully employed to overcome these faults. The desirabihty 
of pasteurizing milk for cheese making, if possible, has often been 
pointed out. 

In 1907 a few lots of milk were pasteurized in a discontinuous 
pasteurizer and acidulated with hydrochloric acid, and the cheese 
obtained was such as to demonstrate the importance of further 
study. 

In 1908 equally good results were obtained by use of the contin- 
uous pasteurizer. A temperature of 160° to 165° was decided upon 
as behig suHiciently high to effectually check bacterial action in 
milk for cheese-making purposes. Bacterial counts showed that 
over 99 per cent of the total bacterial content of the milk was de- 
stroyed at this temperature. The use of higher temperatures was 
shown to be objectionable on account of the effect upon the quality 
of the cheese. 

In 1909 cheese was made almost daily both by the regular factory 
process and by the new process from pasteurized milk. The regular 
milk supply was thoroughly mixed each day and divided into two 
lots for the two different processes. The cheese made from pasteur- 
ized milk was found after curing to be cleaner m flavor and superior 
in texture to the raw-milk cheese. The difference was more marked 
the poorer the quality of the milk supply. Many of the details of 
the process were studied and improved. 



92 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

In 1910 the making of cheese by the two methods for comparison 
was continued, and the entire output of pasteurized-milk cheese was 
sokl to retail grocers, mostly in the city of Madison, in order to 
determine how this cheese would suit the trade. The cheese met 
with ready and continued sale. It w^as noticed also that the yield 
of clieese was, regularly, somewhat greater by the new process than 
by the old. 

In 1911 better facilities were provided for weighing large quan- 
tities of milk and cheese quickly and accurately, and the yields of 
cheese obtained from raw and pasteurized milk were carefully de- 
termined. The accuracy of the experimental methods was such 
that in making duplicate vats of cheese from pasteurized milk the 
yields differed by only 0.58 per cent on the average. A greater 
yield of cheese was always obtained from the pasteurized milk than 
from raw milk, and during the year 1911 the average gain in yield 
of green cheese was 5.37 per cent. However, the green pasteurized- 
milk cheese shrank a httle more than the raw-milk cheese, so that 
when paraffined the average gain in yield from pasteurized milk was 
4.76 per cent. After curing cheese at 60° to 70° F. for about 100 
days, the gain in yield of pasteurized-milk cheese over the raw was 
4.22 per cent. 

SOME ADVANTAGES FROM THE USE OF PASTEURIZED MILK AND HYDRO- 
CHLORIC ACID. 

The average loss of fat in whey from pasteurized-acidulated milk 
is about 0.17 per cent measured at the time the whey is drawn fi'om 
the vat. This is less than half the loss in average factories using 
raw milk. The total loss of fat m whey and drippings from vat and 
press, using pasteurized milk with acid, averaged 1.58 per cent of the 
weight of the cheese, or less than one-half of the usual loss in han- 
dling raw milk. 

In addition to this saving of fat, it is found that a somewhat larger 
proportion of moisture can be incorporated in pasteurized-milk 
cheese than in ordinary cheese, without damage to the quality. 
The gain in the yield of pasteurized-milk cheese is due partly to fat 
and partly to moisture. 

Scores and criticisms made by competent cheese judges show 
that the pasteurized-milk cheese varies less in quality and averages 
better by 3.7 points of total score than the raw-milk cheese made 
from portions of the same milk supply. In 96 per cent of aU cases 
the pasteurized-milk cheese scored higher than the raw-milk cheese. 

Duplicate sets of cheese were cured at New Orleans for one month 
at 70° to 83° (monthly average figures during the summer), and here 
the raw milk lost more in weight than the pasteurized, so that the 
average gain in yield of pasteurized over raw rose to 6.21 per cent. 



OUTLINE OF THE NEW METHOD. 93 

From other cheese cured at Madison on tin pans in a warm room, it 
was learned that the raw-milk cheese lost considerable amounts of 
fat at 75° to 85° while the pasteurized-milk cheese lost none. 

Storage for a month at an average temperature of 75° to 80° at 
New Orleans is not recommended for an}^ cheese, yet it was found 
that pasteurized-milk cheese averaged 3 to 8 points bettor hi total 
score after such storage than raw-milk cheese. 

Since pasteurized-milk cheese can be cured without injury at 70°, 
it is likely that in most cases the expense of cold storage for this 
cheese can be avoided. 

Pasteurized-milk cheese can be put bito cold storage at 34° at the 
age of one week and possibly earlier without injur3^ The earlier 
the cheese can be put in storage, if this is done at all, the greater Avill 
be the gain in yield by the new process. It is planned to study the 
cold storage of this cheese further. 

During 1910-1911 about $2,100 worth of pasteurized-milk cheese 
was sold to about 50 dealers, both wholesale and retail, in various 
large cities from New York to San Francisco. The che(>se sold 
readily for the ruling market prices and often above. Very few 
dealers offered any objections to them and several wislu^d to buy 
them regularly. A good many wer(^ sold throughout tlu^ South by 
dealers. In general, the cheese passed through the market without 
excituig special comment, selling for full price and giving satisfaction. 
They were not labeled or marked except with a number for purposes 
of identification. Th(>re appears to be no reason why ])asteurized- 
milk cheese can not be sold regularly in any market with entire 
satisfaction, exce])tiiig possibly to the limited trade that demands 
very high-flavored cheese. 

OUTLINE OF THE NEW METHOD. 

In the method liere described a ))ri7U'iple is ap|)lied to the cheese- 
making process which has already been found useful in many other 
lines of manufacture, namely: 

The raw material, milk, is first treated by a preparatory process 
to bring it into uniform coniUtion before it enters the manufacturing 
process proper. Material of uniform quaUty thus prepared is made 
up into the finished product b}^ a uniform routine process without 
daily variations of the time schedule or other details, and the product 
is more uniform in quality, has better keeping quahties, etc., than 
the product obtained by the older process. 

The difficulties met with, liitherto in making American Clieddar 
cheese from pasteurized milk are: 

First. That heated milk coagulates poorly with rennet; and 

Second. The curd when obtained does not expel moisture pre- 
cisely as a raw-milk curd does, and this effect is more marked the 



94 CHEDDAR CHEESE FROM PASTEURIZED MILK. 

higher the temperature of pasteurization. The quahty and behavior 
of pasteurized-milk curd suggest that it lacks the acid which is 
normally produced in raw-milk curds by the action of bacteria on 
milk sugar. 

The first of these difficulties, but not the second, can be over- 
come by adding calcium-chlorid solution to pasteurized milk. This 
method has been tried experimentally, but is not recommended for 
use in American cheese factories. Both difficulties, however, are over- 
come by adding an acid, preferably hydrochloric, to the pasteurized 
milk. Hydrocliloric acid is normally present in the human stomach 
during the process of digestion in larger proportions than that added 
to milk in this process of cheese making. Further, 95 per cent of the 
added acid passes out of the cheese with the whey during the process 
of manufacture. On tliis account no objection can be made on 
sanitary grounds to the use of this acid in the manner and for the 
purposes described. 

Among different lots of cheese, part of wliich was made with 
hydrochloric acid and part with calcium chlorid added to portions 
of the same milk after pasteurization, those made with acid were 
found to be more uniform in moisture content and superior both in 
flavor and texture to those made with calcium chlorid. The losses 
of fat in the whey are reduced by the use of the acid. Pasteuriza- 
tion and acidulation of milk for cheese making appear to be com- 
plementary processes. ITsed together they furnish a means for 
bringing milk daily into uniform condition both as to acidity and 
bacterial content for cheese-making purposes. 

The acidulation of milk with hydrochloric acid after pasteuriza- 
tion is accomphshed without difficulty or danger of curdhng by 
running a small stream of the acid, of normal concentration, into 
the cooled milk as it flows from the continuous pasteurizer into 
the cheese vat. One pound of normal-strength acid is sufficient to 
raise 100 pounds of milk from 0.16 per cent to 0.25 per cent acidity 
(calculated as per cent of lactic acid). The amount of acid needed 
each day to bring the milk up to 0.25 per cent acidity is read from 
a table or calculated from the weight of the milk and its acidity, 
determined by the use of Manns's acid test (titration with tenth- 
normal sodium hydrate and phenolphthalein). The preparation of 
standard-strength acid in carboy lots for tliis work and the acidula- 
tion of milk present no great difficulty to anyone who is able to 
handle Manns's acid test correctly. 

After the milk is pasteurized and acidulated three-fourths per 
cent of first-class starter is added and the vat is heated to 85°. It 
is set with, rennet, using 2 ounces of rennet per thousand pounds 
of milk, so that the milk begins to curdle in 7 minutes and is cut 
with three-eighth inch knives in 25 minutes. All portions of the 



OUTLINE OF THE NEW METHOD. 95 

work after addinj^: rennet are carried out in an unvarying routine 
manner, according to a fixed- time schedule every day. As soon 
as the rennet has been added the cheese maker is able to calculate 
the exact time of day wlien each of the succeeding operations should 
be performed, and the work of making the cheese is thus simplified 
and systematized. It is possible that the routine process here de- 
scribed maybe varied somowliat with advantage at different factories. 
For example, some experienced cheese makers may prefer to mat the 
curds on the bottom of the vat instead of on racks or may find the 
use of the "curd gauge" unnecessary, and local conditions may 
be found in {hfl"erent factories making other adjustments of details 
desirable. However, the experience already had with the process indi- 
cates that the routine of daily operations found suitable at any fac- 
tory can be practiced there throughout the season without variation. 

It is the intention to give the new process a tliorougli trial in 
different cheese factc^-ies in various localities to test its applica- 
bility to different milk supplies before recommending it for general 
use by cheese makers. These trials will show whether new diffi- 
culties may arise wliich were not encountered heretofore. Cheese 
makers are therefore advised to await the publication of results of 
further trials of tlie method by the writers before undertaking to 
use the new process at their factories. 

The extra cost of making pasteurized-milk cheese is being studied 
with a view to finding out accurately what the net profit is in making 
this clieese compared with the regular process. 

The new process sliould interest the farmer because of tlie increased 
yield and the avoidance of the usual losses in yield and quality of 
cheese due to defective milk. It should interest the cheese maker 
because the process of making is systematized to such a degree that 
it is conducted upon a fixed-time schedule for all operations. It 
should interest the dealer because the cheese is more uniform in 
quahty and there is less need for cold storage in curing. Finally, 
the cheese should interest the consumer, because it is more uniform 
in flavor than most of the cheese to be found on retail counters and 
because it is made from pasteurized milk and is therefore a more 
sanitary product than ordinary American cheese made from raw 
milk. 



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S\- may be procured from the SuPERfNTEND- 
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